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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

C 1*3 

M- 10 

GEOLOGY 



ANDREW C. LAWSON 

AND 

JOHN C. MERRIAM 

EDITORS 



VOLUME X 
WITH 38 PLATES 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 
1916-1918 



J 4W 5 - ?9?r 



LIBRARY OF CONGRESS 

FEB 281921 

DOCUMENTS DIVISION 



CONTENTS 

PAGE 

No. 1. The Correlation of the Pre-Cambrian Rocks of the Region of the Great 

Lakes, by Andrew C. Lawson 1 

No. 2. A New Mustelid from the Thousand Creek Pliocene of Nevada, by 

Emerson M. Butterworth 21 

No. 3. The Occurrence of Ore on the Limestone Side of Garnet Zones, by 

Joseph B. Umpleby 25 

No. 4. Fauna of the Fernando of Los Angeles, by Clarence L. Moody 39 

No. 5. Notes on the Marine Triassic Reptile Fauna of Spitzbergen, by Carl 

Wiman 63 

No. 6. New Mammalian Faunas from Miocene Sediments near Tehachapi Pass 

in the Southern Sierra Nevada, by John P. Buwalda 75 

No. 7. An American Pliocene Bear, by John C. Merriam, Chester Stock, and 

Clarence L. Moody.... 87 

No. 8. Mammalian Remains from the Chanac Formation of the Tejon Hills 

California, by John C. Merriam Ill 

No. 9. Mammalian Remains from a Late Tertiary Formation at Ironside, 

Oregon, by John C. Merriam 129 

No. 10. Recent Studies on the Skull and Dentition of Nothrotherium from 

Rancho La Brea, by Chester Stock 137 

No. 11. Further Observations on the Skull Structure of ' Mylodont Sloths from 

Rancho La Brea, by Chester Stock 165 

No. 12. Systematic Position of Several American Tertiary Lagomorphs, by 

Lee Raymond Dice 179 

No. 13. New Fossil Corals from the Pacific Coast, by Jorgen O. Nomland 185 

No. 14. The Etchegoin Pliocene of Middle California, by Jorgen 0. Nomland .... 191 
No. 15. Age of Strata Referred to the Ellensburg Formation in the White 

Bluffs of the Columbia River, by John C. Merriam and John P. 

Buwalda 255 

No. 16. Structui of the Pes in Mylodon Harlani, by Chester Stock 267 

No. 17. An Extinct Toad from Rancho La Brea, by Charles Lewis Camp 287 

No. 18. Fauna of the Santa Margarita Beds in the North Coalinga Region of 

California, by Jorgen 0. Nomland 293 

No. 19. Minerals Associated with the Crystalline Limestone at Crestmore, 

Riverside County, California, by Arthur S. Eakle 327 

No. 20. The Geology and Ore Deposits of the Leona Rhyolite, by Clifton W. 

Clark 361 

No. 21. The Breccias of the Mariposa Formation in the Vicinity of Colfax, 

California, by Clarence L. Moody 383 

No. 22. Relationships of Pliocene Mammalian Faunas from the Pacific Coast 

and Great Basin Provinces oi North America, by John C. Merriam . 421 
No. 23. Anticlines near Sunshine, Park County, Wyoming, by C. L. Moody and 

N. L. Taliaferro 445 

No. 24. The Pleistocene Fauna of Hawver Cave, by Chester Stock 461 

No. 25. Evidence of Mammalian Palaeontology Relating to the Age of Lake 

Lahontan, by John C. Merriam 517 

No. 26. New Mammalia from the Idaho Formation, by John C. Merriam 523 

No. 27. Note on the Systematic Position of the Wolves of the Canis Dims 

Group, by John C. Merriam 531 

No. 28. New Puma-like Cat from Rancho La Brea, by John C. Merriam 535 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 1, pp. 1-19 Issued April 27, 1916 



THE CORRELATION OF THE PRE-CAMBRIAN 
ROCKS OF THE REGION OF THE 
GREAT LAKES 



BY 

ANDREW C. LAWSON 



UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



Note. — The University of California Publications are offered in exchange for the publi- 
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Geology. — Andrew C. Lawson and John C. Merriam, Editors. Price, volumes 1-7, $3.50, 
volumes 8 and following, $5.00. 

Cited as Univ. Calif. Publ. Bull. Dept. Geol. 

Volume 1, 1893-1896, 435 pp., with 18 plates, price $3.50 

Volume 2, 1896-1902, 457 pp., with 17 plates and 1 map, price $3.50 

Volume '3, 1902-1904, 482 pp., with 51 plates, price $3.50 

Volume 4, 1905-1906,-478 pp., with 51 plates, price $3.50 

Volume 5, 1906-1910, 458 pp., with 42 plates, price $3.50 

A list of titles in volumes 1 to 5 will be sent upon request. 



VOLUME 6. 

1. The Condor-like Vultures of Eancho La Brea, by Loye Holmes Miller 15fl 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part I. — Geologic History 50c 

3. The Geology of the Sargent Oil Field, by William F. Jones 25c 

4. Additions to the Avifauna of the Pleistocene Deposits at Fossil Lake, Oregon, by 

Loye Holmes Miller 10c 

5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe, by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of Eancho La Brea, by John C. 

Merriam. , 

7. A Collection of Mammalian Eemains from Tertiary Beds on the Mohave Desert, 

by John C. Merriam. 

Nos. 6 and 7 in one cover 10" 

8. The Stratigraphic and Faunal Relations of the Martinez Formation to the Chico 

and Tejon North of Mount Diablo, by Eoy E. Dickerson 5c 

9. Neocolemanite, a Variety of Colemanite, and Howlite from Lang, Los Angeles 

County, California, by Arthur S. Eakle 10c 

10. A New Antelope from the Pleistocene of Eancho La Brea, by Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part II. — Vertebrate Faunas 1.00 

12. A Series of Eagle Tarsi from the Pleistocene of Eancho La Brea, by Loye Holmes 

Miller ^ _ _. lOe 

13. Notes on the Eelationships of the Marine Saurian Fauna Described from the Triassic 

of Spitzbergen by Wiman, by John C. Merriam. 

14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13 and 14 in one cover 15c 

15. Notes on the Later Cenozoic History of the Mohave Desert Eegion in Southeastern 

California, by Charles Laurence Baker 50c 

16. Avifauna of the Pleistocene Cave Deposits of California, by Loye Holmes Miller .... 15c 

17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5> 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Eeid 25c 



VOLUME 7. 

1. The Minerals of Tonopah, Nevada, by Arthur S. Eakle 25 

2. Pseudostratification in Santa Barbara County, California, by George Davis Louder- 

back 2( ; tt 

3. Eecent Discoveries of Carnivora in the Pleistocene of Eancho La Brea, by John C. 

Merriam 5 

4. The Neocene Section at Kirker Pass on the North Side of Mount Diablo, by Bruce 

L. Clark 15 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60' 3 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 1, pp. 1-19 Issued April 27, 1916 



THE CORRELATION OF THE PRE-CAMBRIAN 
ROCKS OF THE REGION OF THE 
GREAT LAKES 

BY 

ANDEEW C. LAWSON 



CONTENTS 

PAGE 



Introduction 1 

Utility of Tentative Correlations 2 

Criteria of Pre-Cambrian Correlation 4 

Hypothesis of Two Periods of Granitic Invasion 5 

Application of the Hypothesis 6 

Northwest of Lake Superior 6 

South of Lake Superior 8 

North of Lake Huron 10 

Southeastern Ontario and Adirondacks 11 

Summary 12 

Events Connected with Granitic Invasion 12 

Departures from Unanimity 13 

Petrographical Discrimination of the Two Granites 15 

Subdivisions of Time — Nomenclature 16 



INTEODUCTION 

The meeting of the International Geological CongTess at Toronto 
in 1913 seems to have marked a new epoch in the history of our ideas 
of the pre-Cambrian of the region of the Great Lakes. The papers 
which were presented at that meeting and which have appeared since 
then, comprising new field observations extending from Rainy Lake to 
the Adirondacks and embracing both sides of Lake Superior, not only 
indicate a renewal of interest in the problems of pre-Cambrian geology, 



2 



University of California Publications in Geology [Vol. 10 



but they contain data and hypotheses of prime importance for the 
solution of those problems. 

A review of the results of this new work, together with the more 
reliable and generally accepted conclusions of earlier investigations, 
show a very remarkable unanimity among the students of separate 
districts distributed over the entire region. There still remain, of 
course, certain outstanding differences of opinion over questions of 
correlation, and particularly as to the use of terms; but if, for the 
moment, we disregard names and the correlations which they imply, 
and focus our attention on the great and fundamental fact of sequence 
of formations and events, an astonishing sameness of result appears in 
a score of districts where more or less detailed work has been done. It 
is the purpose of this paper to make use of this similarity of sequence, 
together with a new hypothesis to be formulated in the sequel, in an 
effort to correlate in a comprehensive way the geological history of 
these districts with one another. The result of this effort is sum- 
marized in the tabulation which accompanies the paper. 



UTILITY OF TENTATIVE CORRELATIONS 

Some writers, notably Collins 1 of the Geological Survey of Canada, 
incline to the view that we can make real progress only by abandoning 
for the present all effort at a general classification of the pre-Cambrian 
formations and concentrating our attention on particular sections 
which are favorable for study, and which are near enough to permit 
of sure correlations from one to the other ; and so gradually widen an 
area within which a classification may be established unvitiated by 
the errors of distant correlation. 

This policy as voiced by Collins is a safe one for the survey to lay 
down, and if pursued consistently will undoubtedly lead to positive 
results. It is a matter for congratulation that we have this prospect of 
close and detailed work on the part of the Canadian geologists, and it 
is to be hoped that more men will engage in it. In the vastness of the 
pre-Cambrian terranes of Canada and the multiplicity of problems 
which they present, there is every justification for the survey devoting 
more of its energies to this field. 

But the method advocated by Collins, while most commendable, is 
not the only one which will contribute to the solution of the general 

i A classification of the pre-Cambrian formations in the region east of Lake 
Superior, Congres geologique international, 1913. 



I 916 ] Lawson: Correlation of Pre-Cambrian Rocks 



3 



problem. "Workers in particular closely grouped fields may ignore the 
work going on in other fields and publish their observations as if the 
latter did not exist, and so, perhaps, promote the intensity of their own 
activity ; but this attitude after all is only an expression of the prin- 
ciple of subdivision of labor, and implies that others must do the 
equally important work of collation, comparison and generalization. 
Every competent attempt at generalization from a reasonable amount 
of data is a step in advance in so far as it corrects the errors of earlier 
efforts. The discarded generalizations, the succession of which creates 
so much disgust in the minds of some, are merely hypotheses which 
have served their purpose and have been supplanted by others which, 
in most cases, are nearer the truth. The normal procedure in scien- 
tific progress is the modification of hypotheses, and the discarding of 
generalizations as expressed in correlation tables, etc., is only an ex- 
emplification of this procedure. The odium which attaches to errone- 
ous correlation tables fades away when we regard them in their true 
light as hypotheses put forward to stimulate inquiry as to their 
validity. 

These hypotheses are the more necessary and the more useful in 
geology because of the vastness of the field of observation, the expense 
attaching to the work, and in pre-Cambrian geology, because of an 
international boundary which precludes survey officers of one country 
from fully familiarizing themselves with the field relations in the other. 
These conditions make it impossible for the individual geologist thor- 
oughly to test a hypothesis that may explain his own particular field, 
and he is under the necessity of publishing it in order to secure co- 
operative criticism from other fields. In most other sciences the indi- 
vidual worker may more conveniently put his hypothesis to the test 
before publication, and there are in these sciences doubtless as many 
discarded hypotheses as in geology, though perhaps not so many have 
been published. 

Having thus persuaded myself that tentative generalizations are a 
useful if not a necessary part of the method of advancing our knowl- 
edge of pre-Cambrian geology, I shall proceed to review briefly some 
phases of our present knowledge of this field and to formulate still 
another correlation table. I am moved the more to do this because of 
the recent publication of a correlation table by Allen and Barrett, 2 to 
certain parts of which I dissent on the ground that it does not take 
sufficient cognizance of the relationships established in other fields. 

2 Jouru. Geol., vol. 23, no. 8, p. 689, 1915. 



4 



University of California Publications in Geology [Vol. 10 



CRITEEIA OF PRE-CAMBEIAN CORRELATION 
The table which I offer for consideration is designed to be more 
than an alternative to that of Allen and Barrett, in that it exemplifies 
the application of a principle in the correlation of the pre-Cambrian, 
which if true, should be of great interest and service to students in 
this general field. 

The work of Allen and Barrett on the pre-Cambrian sequence and 
structure of the Gogebic range is of a high order. These geologists 
appear to have been actuated, however, by the principle, laid down 
by Collins, of every man confining himself to his own bailiwick ; and 
they do not discuss the relation of their own very important discoveries 
to the general problem of the classification and correlation of the pre- 
Cambrian. Yet, in the use of such terms as Huronian and Animikie 
for major subdivisions of their sequence, they imply correlations and 
conclusions which are at variance with the recent results of Collins 3 
obtained on the north side of Lake Huron by methods quite as thorough 
and reliable as their own. Indeed, it would be difficult to find a more 
striking illustration of the infelicity of the exclusive method, of ignor- 
ing what others are doing, than is afforded by a comparison of the use 
of terms in the papers by Collins on the one hand and by Allen and 
Barrett on the other. 

The correlation table here presented contains fifteen columns show- 
ing the pre-Cambrian sequence in as many different districts dis- 
tributed over the region of the Great Lakes from Rainy Lake to the 
Adirondacks. The sequence in every district, with one exception, 
column XI, is practically undisputed. The columns may be placed 
side by side in various ways so as to suggest various correlations ac- 
cording to the views of the correlator and the guiding principle of 
correlation adopted by him. The difficulty of finding principles suffi- 
ciently reliable to establish correlations in the pre-Cambrian is well 
known. Those that have been used by geologists up to the present are 
chiefly : ( 1 ) The principle of lithologic similarity and the community 
of conditions of deposition inferred from this similarity. (2) The 
principle of the similarity of sequence. (3) The principle of coinci- 
dence of unconformities in the sequence. (4) The principle of irrup- 
tive contacts. 

By diligent and repeated application of these principles numerous 
attempts at correlation have been made, each one seeking to improve on 

3 The Huronian Formations of the Temiskaming Region, Canada, Geol. Sur- 
vey of Canada, Mus. Bulls, nos. 8, 1914, and 22, 1916. 



1916] 



Lawson: Correlation of Pre-Cambrian Rocks 



5 



its predecessor as new similarities or dissimilarities were detected, as 
the members of the sequence increased in number, and as new uncon- 
formities or irruptive contacts were discovered. The Keewatin was 
segregated from the Huronian on the basis of its dissimilarity and the 
intrusive relations of the Laurentian granite gneiss. The iron-bearing 
rocks of the south side of Lake Superior were correlated with the Ani- 
mikian on the basis of lithologic similarity and their unconformable 
relation to the Keweenawan above and to an older complex below. The 
Keweenawan of the north shore has been satisfactorily correlated with 
the rocks so named on the south shore on the basis of lithologic re- 
semblance. The Huronian has been divided into three parts by two 
unconformities discovered within the original Huronian terrane and 
the correlative of these parts is claimed to have been found in various 
districts on the basis of lithologic resemblance, sequence and coinci- 
dence of unconformities. In this way much progress lias been made 
and our knowledge of the pre-Cambrian has advanced greatly in the 
last three decades. 

It is evident, however, when we review the literature and note the 
wide differences of opinion regarding the correlation of some undis- 
puted sequences, that the principles hitherto invoked are not wholly 
adequate for the purpose. "When fossils were found in the limestones 
of Steeprock Lake in 1911, it was my hope that the same forms might 
be found in similar limestones on the south side of Lake Superior and 
so confirm the correlation tentatively adopted. This expectation, how- 
ever, has not yet been realized. 

HYPOTHESIS OF TWO PERIODS OF GRANITIC INVASION 

In the correlation table here formulated a new hypothesis is intro- 
duced and used as an aid to correlation, which, if it is true, resolves 
much of the doubt which has troubled students of pre-Cambrian 
geology. This hypothesis states that in post-Keewatin time there were 
two and only two periods in which great granitic batholiths were 
developed in the earth 's crust in the region of the present Great Lakes. 

It is intended in this hypothesis to exclude certain acid "red 
rocks" found intrusive in the Keweenawan as not batholithic masses 
and as easily distinguishable ordinarily from the granites to which 
reference is here made. It is also intended in each batholithic period 
to include all of the various satellitic rocks that pertain to granites, 
such as pegmatites, aplites, etc., and also certain sequences in the ir- 



(i 



University of California Publications in Geology [Vol. 10 



ruptive process connected presumably with magmatic differentiation. 
In general, there is little danger of confounding the various mani- 
festations of batholithic development, such as a sequence of plutonic 
rocks from basic to acid, of one period with those of the other when 
both are represented in the same field. Where the batholithic assem- 
blage of only one period is represented in a particular field there may 
be doubt ; but this may usually be resolved by an appeal to other means 
of correlation with neighboring fields where granites of both periods 
are represented. Moreover, it seems not improbable that purely petro- 
graphieal distinctions between the granites of the two periods may be 
recognized which will aid in their discrimination. 

APPLICATION OF THE HYPOTHESIS 

The justification of the hypothesis of two and only two granitic 
assemblages in the post-Keewatin rocks of the region of the Great 
Lakes is the fact that in the greater number of the districts repre- 
sented in the accompanying tabulation there actually are two granites 
widely spaced in time. The hypothesis states that the earlier granite 
in every district was formed during one and the same general period of 
time, and that the later granite belongs to another period, the same 
for all districts. These two granitic assemblages have frequently been 
confused by a reference of both of them to the Laurentian, but with 
the increase of detailed studies their separation in time has become 
apparent in many districts. 

Nortltwest of Lake Superior. — In my work on the northwest side of 
Lake Superior in 1911 I was so impressed with the importance of this 
separation that, in order to secure its recognition, and so do away with 
the confusion which had arisen from the indiscriminate reference of 
all granites to the Laurentian, I proposed that the latter term be re- 
tained for the older assemblage and a new term, Algoman, be em- 
ployed to designate the later assemblage. On the northwest side of 
Lake Superior there are six separate and well distributed districts 
which have been more or less carefully studied, and for each of which 
we have the necessary data for the formulation of the geological 
column in the proper chronological sequence. These are : Rainy Lake, 
Steeprock Lake, Thunder Bay, Gunflint Lake, Vermilion Lake, and 
the Mesabi Range. 

Running through all of these districts is a relatively persistent 
series of formations comprising conglomerate, quartzite, graywacke, 



1916] Lawson: Correlation of Pre-Cambrian Rocks 



slate, and lenses of iron formation and iron ore. This is recognized 
in the Mesabi, Vermilion, Gunflint and Thunder Bay districts as 
the Knife Lake slate and Ogishke conglomerate. From Rainy Lake to 
Steeprock Lake, and beyond to the eastward, the series is continu- 
ously exposed. No one questions the identity of the series in the sev- 
eral districts, and it seems fairly certain that it is the product of con- 
tinuous sedimentation in a definite, unbroken period of time. Tem- 
porarily I shall refer to it as the Seine Series and to the corresponding 
division of time as the Seine Epoch, without prejudice to any more 
acceptable designation that may be claimed for it later on the basis of 
correlation. The present distribution of the remnants of the Seine 
Series, taken in connection with its remarkably uniform lithologic 
habit, warrants the belief that originally it must have covered an area 
in this portion of the region of at least 10,000 square miles as a con- 
tinuous body of sediments. 

In all of the districts named above, the Seine Series rests upon the 
eroded surface of a complex consisting of the Keewatin invaded by 
granite and granite gneiss of varying facies, with the usual accom- 
paniment of pegmatites, aplites and other differentiation products of 
batholithic development. This granite and granite gneiss may most 
conveniently be known as Laurentian in accordance with prevailing 
usage. It is therefore certain that throughout all of the studied dis- 
tricts in the portion of the region lying to the northwest of Lake 
Superior, the earth's crust was invaded by granite in time long ante- 
cedent to the deposition of the Seine Series and that this granite is 
post-Keewatin in age. It is most probably all of the same age, i.e., it 
was all formed in the same large division of time which, in the chrono- 
logical scale, may be known as the Laurentian Revolution. 

Now the Seine Series is, in every one of the six districts named, 
itself cut by granite and granite gneiss of varying facies with peg- 
matites, aplite and other differentiation products, constituting a 
granitic assemblage which, from its vast areal extent, may be regarded 
as a manifestation of batholithic invasion. To this granite I have 
given the name of Algoman in a comprehensive sense, so that the period 
of time in which it was formed may be known as the Algoman, a term 
co-ordinate with Laurentian in the chronological scale. 

It is thus again certain that in all the studied districts northwest 
of Lake Superior the earth's crust was invaded by granite in time 
subsequent to the deposition of the Seine Series. It is equally certain 
that this Algoman granite long antedates the Animikian Series, of 



8 



University of California Publications in Geology [Vol. 10 



the original Animikie area, since these rocks may be observed in four 
of the districts resting on the eroded surface of the granite in rela- 
tions so clear that they have never been questioned. In the Rainy 
Lake and Steeprock Lake Districts the Animikian is absent. 

There is no room for doubt, therefore, that on the northwest side of 
Lake Superior the Algoman granite was formed within the space of 
time between the close of the Seine Epoch and the beginning of the 
Animikian. It is highly probable on the basis of areal continuity 
that in all the districts the Algoman granite is the manifestation of 
one and the same general disturbance and batholithic invasion of the 
earth's crust. The assumption that this is so is involved in the use of 
the term Algoman as a designation for these rocks considered as a con- 
stituent part of the earth's crust and in the use of the same term as 
a designation for a subdivision of geological time. 

From the foregoing discussion it is apparent that the Laurentian 
and Algoman granites afford us two splendid datum planes along 
which we may correlate from district to district with a confidence pro- 
portionate to the validity of the hypothesis of a definite proper age for 
each granite. In the correlation table columns I to VI, representing 
the sequences in the different districts, are placed side by side with 
the granites arranged each on a horizontal line. The correlation thus 
suggested is that which is generally accepted for the non-plutonic for- 
mations of the pre-Cambrian of the northwest side of Lake Superior. 

South of Lake Superior. — On the south side of Lake Superior four 
of the more important and best-known districts, namely, Gogebic, 
Crystal Falls, Menominee, and Marquette, have been selected for con- 
sideration in the correlation table. In each of these districts there is 
found a group of formations comprising a basal quartzite and an 
overlying dolomite. In the Gogebic district these are known as the 
Sunday quartzite and the Bad River dolomite, in the Crystal Falls 
and Menominee districts as the Sturgeon quartzite and the Randville 
dolomite, and in the Marquette district as the Mesnard quartzite and 
the Kona dolomite. All the geologists who have studied these districts 
are now agreed as to the identity of this pair of formations in all four 
districts and their correlation is not questioned. The quartzite and 
dolomite, by whatever local name known, together represent a definite 
stratigraphic horizon and a definite period of time. Now the quartzite 
in all four districts rests with a basal conglomerate upon the eroded 
surface of granite-gneiss which has been referred to the Laurentian, 
or upon the Keewatin into which the latter is intrusive. It is there- 



1916] 



Lawson: Correlation of Prc-Cambrian Rocks 



9 



fore fairly certain that the group comprising the quartzite and dolo- 
mite is later than this Laurentian granite gneiss throughout the four 
districts. 

Resting unconformably on the quartzite-dolomite group in all four 
districts is another group comprising in the Gogebic district the Palms 
quartzite, graywacke and slate, the Ironwood iron formation, and the 
Tyler slates ; in the Crystal Falls district the Ajibik quartzite, the Vul- 
can iron formation and the Hanbury slates ; in the Menominee dis- 
trict quartzite, Vulcan iron formation and Hanbury slates ; and in 
the Marquette district the Ajibik quartzite, the Siamo slate and the 
Negaunee iron formation. Here, again, there is little doubt as to the 
correlation of this group of variously named formations throughout 
all four districts. The group, with local volcanic admixtures, repre- 
sents a definite stratigraphic horizon and a definite period of time 
which is the same in all districts. 

In the Gogebic district the group is cut by the Presque Isle granite, 
as Allen and Barrett have recently shown, 4 and in the Menominee dis- 
trict the group is also cut by granite. It is therefore certain that, at 
a time later than the accumulation of this group of variously named 
formations, there was a plutonic invasion of the earth's crust by 
granite on the south side of Lake Superior. 

Thus we have on the south side of the lake, as on the northwest 
side, two and (so far as we know) only two periods of batholithic in- 
vasion. The corresponding granites serve as on the northwest side to 
separate the geological column into three great divisions, one ante- 
cedent to the first granite, the second between the two granites and 
the third subsequent to the second granite. It is the essence of the 
hypothesis which I here advance as a tentative principle of pre- 
Cambrian correlation, that the two granite invasions of the south side 
of Lake Superior are chronologically equivalent to the two granite in- 
vasions of the northwest side, each to each. 

In accordance with this hypothesis the columns expressing the un- 
disputed sequence in the Gogebic, Crystal Falls, Menominee, and Mar- 
quette districts are placed in the tabulation with the two granites on 
the same time-horizons as the two granites of the northwest side of the 
lake. It follows, if the hypothesis is true, that the group of variously 
named formations on the south side, comprising the Tyler and Han- 
bury slates, the Ironwood, Negaunee, and Vulcan iron formations, and 
the Palms, Siamo, and Ajibik formations, are the correlatives of the 

4 Journ. Geol., vol. 23, do. 8, Nov. -Doc, 1915. 



10 



University of California Publications in Geology [Vol. 10 



group of variously named formations on the northwest side compris- 
ing the Seine slate, quartzite and conglomerate, the Knife slates, 
Agawa iron formation, and Ogishke conglomerate of the northwest 
side. It follows also from the recent work of Allen and Barrett 5 that 
the Copps Formation, the Michigamme slate, the Bijiki iron forma- 
tion, and the Goodrich quartzite of the south side are the correlatives 
of the Animikian of the northwest side of Lake Superior. 

North of Lake Huron. — Coming now to the Canadian territory ex- 
tending from Lake Huron to Lake Temiskaming, there are three gen- 
eral districts in each of which the sequence of the pre-Cambrian rocks 
has been for the most part clearly established. These are the north 
shore of Lake Huron, Sudbury, and Lake Temiskaming. In all three 
districts it is now agreed that in post-Keewatin time there were two 
distinct periods of granitic invasion. It is also undisputed that one 
of these invasions occurred in time long antecedent to the deposition 
of the great body of sedimentary rocks now called the Temiskamian 
(Sudbury) series, and that the second period of granitic invasion is 
later than that series. This fact was well known to Logan and pre- 
cisely described by him in the following words : 

The intrusive granite occupies a considerable area on the coast of Lake Huron, 
south of Lake Pakokagaming. It there breaks through and disturbs the gneiss 
of the Laurentian Series and forms a nucleus from which emanates a complexity 
of dykes, proceeding to considerable distances. As dykes of a similar character 
are met with intersecting the rocks of the Huronian Series (Temiskamian of Miller 
and Knight), the nucleus in question is supposed to be of Huronian age, etc.o 

It seems clear that the older of these granites is what Logan called 
Laurentian and that it is older than the Temiskamian (Sudbury) 
series. The later granite cuts the Temiskamian, as is described by 
Logan, Miller, Coleman, and Collins. In the Sudbury district the 
Temiskamian (Sudbury) series is invaded by granite and the con- 
glomerate of the series contains boulders of granite, although the 
basement is not exposed. In the Cobalt district the Temiskamian 
rests on the eroded surface of the Laurentian granite and is itself in- 
vaded by the Lorrain granite. 

In a recent paper Collins 7 has shown that the later, or Killarney, 
granite also cuts the Bruce series. 

Op. cit. 

« Geology of Canada, p. 58, 1863. 

1 Geol. Survey of Canada, Mus. Bull. no. 22, 1916. 



1916] Lawson: Correlation of Pre-Cambrian Rocks 11 



It thus seems pretty certain that the territory extending from Lake 
Huron to Lake Temiskaming, and including the Lake Huron, Sud- 
bury, and Cobalt districts, suffered granite invasion at two widely 
spaced periods. These two periods of granitic invasion separate the 
sequence of epigene rocks throughout these three districts into three 
parts, precisely in the same way as the two granites on the south side 
of Lake Superior do, and it seems probable that they are chronological 
equivalents each to each. 

If this be true, then it follows that the Temiskamian and Bruce 
series both fall into the middle of the three great divisions of time, 
that is, they were deposited in the period between the degradation of 
the Laurentian and the invasion of the region by the Killarney or 
Lorrain granite. The relations of the Temiskamian to the Bruce series 
have not yet been satisfactorily established, but it seems probable that 
the Bruce series is the equivalent of the Sturgeon quartzite and Kona 
dolomite, etc., of the south side of Lake Superior ; while it is equally 
probable that the Temiskamian is the equivalent of the group of 
variously named formations on the south side comprising the Tyler 
and Hanbury slate, the Ironwood, Negaumee, and V ulcan iron forma- 
tion, the Palms and Ajibik formations, etc., and therefore the correla- 
tive of the Seine Series on the northwest side of Lake Superior. The 
Cobalt Series appears then with little question to be the equivalent of 
the Copps, Michigamme, etc., on the south side and of the Animikian 
of the northwest side. 

Southeastern Ontario and Adirondacks. — In Southeastern Ontario 
there is an older granite gneiss, the Laurentian, cutting the Keewatin 
and Grenville series, and a later, Moira, cutting the Hastings series, 
which rests upon the eroded surface of the Laurentian. These two 
granites, by the hypothesis here advanced, are the respective chrono- 
logical equivalents of the two granites on the north shore of Lake 
Huron, on the south side of Lake Superior and on the northwest side ; 
and the Hastings series is either the correlative of the Temiskamian, 
as Miller and Knight assert, as well as of the Tyler-Hanbury-Palms- 
Siamo-Ajibik, etc., and of the Seine ; or the correlative of the Bruce 
series. 

In the Adirondacks, according to Gushing, 8 there are two granites 
of widely different ages, the Laurentian intrusive in the Grenville, and 
the Pieton, itself undeformed, cutting the Laurentian after the de- 
formation of the latter. 



» Am. Journ. Sci., vol 39, pp. 288-294, March, 1915. 



12 



University of California Publications in Geology [Vol. 10 



Summary. — It thus appears that in every one of the fifteen dis- 
tricts, extending over a belt of the continent nearly a thousand miles 
long and covering both sides of the Great Lakes, we have at least one 
and not more than two periods of granitic invasion well established. 
The older granite is represented in all fifteen districts ; while the 
later granite is found in thirteen districts, failing to appear in the 
Crystal Falls and Marquette, although in the last-named district more 
discriminating study may yet show its presence. In neither of the 
two districts in which only one granite is found is there any doubt as 
to the period to which it belongs. We may safely conclude, there- 
fore, that in every one of the fifteen districts, considered individually, 
geological time is blocked out into three grand divisions by the two 
granite invasions : the pre-granitic, the inter-granitic and the post- 
granitic. It is the essence of the hypothesis here set forth that these 
three divisions of time, which are so well established in the individual 
districts, are the same in all of them, there being but one pre-granitic, 
one inter-granitic and one post-granitic period represented by the 
known epigene rocks throughout the entire region from Rainy Lake 
to the Adirondacks. 

EVENTS CONNECTED WITH GRANITIC INVASION 

Wherever the earth's crust is known to have been extensively in- 
vaded by granite, an important concomitant condition has been the 
uplift of the region affected and the inauguration of a prolonged 
period of degradation, culminating in the removal of the cover from 
extensive areas of the granite. Wherever in the course of time sedi- 
mentation resumed its sway, the resumption was not effective until 
the region had been reduced to a surface of low relief. The time nec- 
essary for the invasion of a region by granite is unknown, but it may 
well have been a long drawn-out process. The stripping of the cover 
of the granite, however, and particularly the reduction of a high 
region to low relief, requires a long time in the geological sense ; and 
the interval of no deposition, between the sediments resting on the 
worn surface of the granite and the sediments into which the granite 
is intrusive, constitutes an unconformity of a major order. We may 
for practical purposes take the appearance of a worn surface of granite 
upon which as a basement sedimentary strata rest as prima facie evi- 
dence of a major unconformity. Now we have such a major uncon- 
formity well revealed on the northwest side of Lake Superior in the 



1916] 



Laivson: Correlation of Prc-Cambrian Rocks 



13 



superposition of the Steeprock series upon the granite of the first, 
or Laurentian, invasion ; on the south side of Lake Superior in the 
superposition of the Sturgeon quartzite upon the Laurentian ; and on 
the north side of Lake Huron in the superposition of the Bruce series 
upon the Laurentian. 9 

Similarly we have another major unconformity equally well estab- 
lished on the northwest side of Lake Superior in the superposition of 
the Animikian upon the granite of the second, or Algoman, invasion ; 
on the south side of Lake Superior in the superposition of the Michi- 
gamme (Copps, etc.) upon the second granite (Presque Isle) ; and on 
the north side of Lake Huron in the superposition of the Cobalt 
series upon the second granite (Lorrain, probably the same as the 
Killarney ) . 

Thus, when by hypothesis we correlate chronologically the pairs of 
granites each to each in the various districts of the tabulation, we are 
in reality correlating in every case a group of interconnected events of 
the first magnitude comprising: 1. The invasion of the crust by 
granite. 2. The uplift of the region. 3. The reduction of the region 
to low relief. This of course greatly strengthens the hypothesis since 
it increases the improbability of there having been a multiplicity of 
chronologically different granitic invasions each with its induced uplift 
and prolonged period of degradation. It also justifies the use of such 
terms as Epilaurentian and Eparchean for subdivisions of geological 
time, since no sediments can have accumulated in any of the districts 
for a long period after each granitic invasion, these periods being re- 
corded in terms of erosion. Geologists who are concerned only with 
the sequence of rocks may dispense with these terms, but those who 
have to deal with the subdivision and correlation of geological time 
defeat their purpose if they ignore those large periods in which no 
sediments are known to have been deposited. 

DEPARTURES PROM UNANIMITY 

It is interesting to note that for the most part the sequences and 
correlations which are set forth in the tabulation are those which 
are generally accepted ; and for the Canadian territory they represent 
the same general conclusions as have been published by Miller and 
Knight, 10 except that these writers have not recognized the dual com- 
position of the Huronian system. There are, however, a few instances 

9 Collins, Geol. Survey of Canada, Mu3. Bull. 8 and 22, 19] (i. 
i<>Ont. Bur. Mines, 22, 2, p. 126, 1914. 



14 



University of California Publications in Geology [Vol. 10 



in which the table differs from the views held by other geologists, and 
to these brief reference may now be made. 

As to sequences, it is first to be noted that Leith 11 is of the opinion 
that in the Mesabi district there is a third granite which cuts the 
Animikian. I have, however, in a former paper 12 pointed out how 
doubtful the evidence of the age of this granite is and, as my skepti- 
cism has deepened, I have omitted it from the table. 

In the Lake Huron section, also, I have taken the liberty of differ- 
ing with Collins in his interpretation of the sequence. In doing this 
I feel that I have not done violence to any direct evidence which he 
has adduced as to the superposition of the Bruce series upon the 
Temiskamian. The hypothesis of two and only two periods of granitic 
invasion has been used to determine what the real sequence is. I have 
placed the Bruce series earlier than the Killarney granite and the 
Cobalt series later, and suggest that the Bruce series lies below the 
Temiskamian, there being no very satisfactory evidence to the con- 
trary. 

In southeastern Ontario there is doubt as to whether the Hastings 
Series is the correlative of the Bruce or the Temiskamian. In the table 
I have followed Miller and Knight who correlate it with the Temis- 
kamian. 

My most serious difference, however, is with Allen and Barrett, not 
as to the sequence on the south side of Lake Superior, but as to the 
correlation of the rocks there with those on the northwest side. As 
a result of some excellent field studies these geologists found 13 that in 
the Gogebic district the rocks heretofore referred to the Animikian 
really comprise two series separated by a major unconformity, involv- 
ing the uncovering and degradation of the Presque Isle granite. This 
granite is the second of two granites which occur in the district and 
the major unconformity corresponds to the Eparchean Interval. Ac- 
cording to the principle of correlation here advanced, the rocks which 
follow the Eparchean Interval, namely, the Copps formation, should 
be correlated with the Animikian of Thunder Bay. Allen and Barrett, 
however, correlate the Tyler slate, etc., into which the Presque Isle 
granite is intrusive, with the Animikian, and make the Copps forma- 
tion and its equivalents post-Animikian, separated by a major uncon- 
formity. This correlation involves the notion of three great granitic 



u U. S. G. S., Mon. 43, p. 411. 

i- Comptes Bendus Cong. geol. internat. XII, 1913, p. 367. 
is Jonrn. Geo!., vol. 23, no. 8, 1915. 



1916] 



Lawson: Correlation of P re-Cambrian Rocks 



15 



invasions in the Lake Superior districts and three major unconformi- 
ties, and this I hold to be a misconception of the geological history of 
the region. 

On the south side of Lake Superior the local correlations advo- 
cated by Allen, which I have for the most part followed in the table, 
are not wholly accepted by Leith. The difference of view is fully set 
forth in recent papers by these writers and need not be restated, since 
they do not affect seriously the main hypothesis of this paper. 

PETROGRAPHICAL DISCRIMINATION OF THE TWO GRANITES 

It would be a matter of great interest and importance if petro- 
graphical criteria could be formulated whereby the Laurentian and 
Algoman plutonic rocks could be discriminated ; but it is probable that 
our studies of these rocks are too little advanced to make such a dis- 
crimination reasonably certain. Nevertheless, since a beginning at 
this discrimination has to be made, I venture to offer some suggestions 
to this end, based chiefly on my own observations : 

1. The Laurentian granite is in general more uniform and monoton- 
ous in mineralogical composition than the Algoman granite. 

2. The Algoman granite has usually undergone magmatic differ- 
entiation to a marked degree and, therefore, has a larger range of 
facies than the Laurentian, being in many areas syenitic rather than 
granitic. 

3. The Laurentian granite had been as a rule subject to deforma- 
tion before the Algoman granite came into existence, and therefore 
may in general be expected to show more pronounced deformational 
effects. 

4. The Algoman granite is in many extensive areas perfectly mas- 
sive and unfoliated and this is rarely true of the Laurentian. 

5. The Laurentian granite is in many areas bleached in appearance, 
whereas the Algoman granite appears fresh and in many cases reddish- 
colored. 

6. The phenomena of viscous flow is more often exemplified in the 
Algoman granite than in the Laurentian. 

7. The minerals nepheline, titanite, apatite, and garnet are per- 
haps more abundant in the Algoman rocks than in the Laurentian. 

8. Intrusive phenomena at the contact with encasing rocks are 
usually clear-cut and pronounced in the case of the Algoman granite 
and are more obscure in the case of Laurentian granite. 



16 



University of California Publications in Geology [Vol. 10 



9. The metamorphism of the rocks encasing the Algoman granite 
is for rocks of pre-Laurentian age additive to an earlier metamor- 
phism, and for rocks of post-Laurentian age not. 

SUBDIVISIONS OF TIME — NOMENCLATURE 
Accepting now the hypothesis of two periods of granitic invasion, 
there remains the question of nomenclature. This has to do with the 
classification of assemblages of rocks and with the subdivision of geo- 
logical time, and the names must be appropriate to both. I have 
shown that pre-Cambrian epigene rocks fall into one or the other of 
three grand divisions of time, and for these divisions it is clear that 
we must have distinctive names. For the first or pre-Laurentian 
division I proposed 14 many years ago the term Ontarian, and this still 
appears to me to be the best term to adopt. It is objected by Miller and 
Knight 15 that this term has been used as a synonym for Silurian. But 
this synonym appears to have been stillborn ; and fortunately so, for 
its use would be a burdensome superfluity. The word is not mentioned 
in the recent work 10 by Schuchert on Historical Geology ; nor is it used 
either in the text or in the tabulation of his more technical paper 17 
presented at the Toronto meeting of the International Geological Con- 
gress. Similarly, Ulrich appears to have no use for the term as a syno- 
nym for Silurian in his papers. 18 If these authorities on the classifi- 
cation of the Paleozoic and many other writers who might be cited 
ignore the word, we may regard it as discarded and so available for 
the use which I suggested in 1889. As for the substitute, Loganian, 
proposed by Miller and Knight, 11 * that is effectively disbarred by the 
general use of the name Logan for the sills of Lake Superior. 20 

Applied to the rocks formed in this period of time, Ontarian ranks 
as a system and embraces the Coutchiching, Keewatin, and Grenville 
series. 

For the second grand division of pre-Cambrian time the term 
Huronian is undoubtedly the most fitting, as well as the most thor- 

14 The Internal Relations and Taxonomy of the Arehean of Central Canada, 
Bull. Geol. Soc. Am., Dee., 1889. 

15 Eevision of pre-Cambrian Classification in Ontario, Journ. Geol., vol. 23, 
1915. 

16 Pirsson and Schuehert, A Text-book of Geology, Part II, 1915. 

i' The Delimitation of the Geologic Period, etc., Cong. geol. internat., 1913. 
18 E.g., Revision of the Paleozoic Systems, Bull. Geol. Soc. Am., vol. 22, pi. 
27, 1911. 
is Op. cit. 

20 The Laeeolithic Sills of the Northwest Coast of Lake Superior, Geol. and 
Nat. Hist. Surv. Minn., Bull. no. 8, 1893. 



1916] 



Lawson: Correlation of P 're-Cambrian Rocks 



17 



oughly established by the rules of priority and respect for the pioneer 
workers in this field. From the point of view of stratigraphy Huron- 
ian is the name of a system and embraces the Bruce Series of Lake 
Huron and its equivalents as well as the Temiskamian and its equiva- 
lents. By adopting these two terms, the first proposed by Collins 21 in 
1914 on behalf of the Geological Survey of Canada and the second by 
Miller 22 in 1911, we avoid the confusion which attaches to the terms 
Upper and Lower Huronian. Coleman 23 has sought to substitute Sud- 
burian for Temiskamian but the latter term has priority and should 
be retained. 

For the third of the grand divisions of pre-Cambrian time repre- 
sented by epigene rocks I propose, as I have done in previous papers, 
the retention of the term Algonkian. A name is needed and I know 
of no better use to which the term Algonkian can be put. The name 
is, I am well aware, in bad repute and nearly meaningless, but I hope 
it may be retained to serve the purpose for which it was originally 
intended, namely, to designate the pre-Cambrian rocks laid down in 
post-Archean time, and as a name for the corresponding period. Thus 
defined, Algonkian is a system embracing the Animikian and the 
Keweenawan. This system might with propriety be included in the 
Paleozoic, to the great simplification of our general scheme of classi- 
fication. 

The Ontarian period is separated from the Huronian by a long 
lapse of time in which no epigene rocks were formed in the region 
considered, nor anywhere else that we have cognizance of. Geological 
processes not less important and even more interesting than sedimenta- 
tion were, however, in operation ; and the record of events and of the 
passage of time is just as clearly marked as it is in other periods by 
the accumulation of strata. These events, from the point of view of 
their distribution in time, comprise: (1) The development of batho- 
lithic magmas accompanied by uplift and acute deformation of the 
crust, and the solidification of these into vast bodies of granite. 
(2) The prolonged degradation of the region and its reduction to a 
surface of low relief. The rocks formed during the first of these two 
time-divisions constitute so important an element in the structure of 
the earth's crust that we can scarcely discuss the problems which they 
present without the retention of the term Laurentian, which has been 

21 The Huronian Formations of Temiskaming Eegion, Canada, Geol. Survey 
of Canada, Mus. Bull. no. 8, p. 26. 

Eng. and Min. Journ., Sept. 30, 1911, p. 648. 
23 Out. Bur. Mines, 23, pi. 1, p. 205, 1914. 



18 



University of California Publications in Geology [Vol. 10 



so long applied to them, and which was adopted by the International 
Committee 24 some years ago. If the name be retained for the rocks, as 
nearly all geologists conversant with this field are agreed, it seems 
proper and convenient to use the same term for the time-division in 
which they were formed. The second division of the lapse between the 
Ontarian and the Huronian is recorded in terms of erosion only. We 
have no rocks to discuss or to name. But to complete the time-scale 
and so keep our ideas on the subdivision of geological time clear, it is 
desirable that we should name this period, and I have in a former 
paper suggested that it be designated the Epilaurentian Interval. 25 

Similarly the Huronian is separated from the Algonkian by the 
time necessary for the development of the Algoman granite, with its 
concomitant diastrophism, and by the succeeding period in which the 
region was reduced to a surface of low relief. These time-divisions I 
have designated the Algoman 20 and the Eparchean Interval. 27 The 
last-mentioned term is much preferable to Epalgomian suggested by 
Schuchert 2S as a substitute for the earlier name, because the interval 
separates the great Archean Era from the Paleozoic. There can be no 
doubt that historically the Huronian is a subdivision of the Archean, 
and its relations to the Algoman are so similar to the relations of the 
Ontarian to the Laurentian, that it is most appropriate to group this 
dual set of relations and geological conditions together under the com- 
prehensive term Archean. In this sense the term designates an era 
of time truly and characteristically archaic, even from a geological 
point of view. The general plan of continental growth in Paleozoic 
time is usually regarded as having been inaugurated with the Cam- 
brian, but in fact it began with the Animikian. At the close of the 
Eparchean Interval the vast continental platform, upon which the 
Paleozoic rocks rest, had been completed. The early Cambrian conti- 
nent of Walcott 28 was but a slightly modified phase of the continent 
upon which the Animikian strata were deposited. It was Animikian 
sedimentation that ushered in the Paleozoic Era. Previous to the 
Eparchean Interval the physiography of the continent had been 
wholly different, and its growth had proceeded on other lines. Events 

24 Journ. Geol., vol. 13, 1905. 

25 A Standard Scale for the pre-Cambrian rocks of North America, Cong, 
geol. internat., XII, 1913. 

26 Cong. geol. internat. XII, 1913. 

27 Bull. Dept. Geol. Univ. Calif., vol. 3, no. 3, 1902. 

28 Text-book of Geology, p. 445, 1915. 

2» U. S. G. S. 12th Ann. Rpt., 1, 1890-91. 



iMBRIAN ON 



VII 

Gogebic 



m 
o 



§ eenawan 
O 

H I 



5j |>s Formation 
P- 1 ate, graywacke, 
!ert, conglomerat* 



EPAi^r unconformity m< *3/ 



lite (Presque Isle in ) 



r slate, volcanics 
wood I. F., Palms 



mformity 



P3 Kiver limestone, 
^ ay quartzite 

«J ■ l 

g ! . 

W j>r unconformity 
M I 1 



lite gneiss 



(vatin 



SOUTHEASTERN DISTRICTS 



XIV 
E. Ontario 



Granite (Moira) 



Hastings 



Major unconformity 



Granite gneiss 



Grenville 



Keewatin 



XV 

Adirondacks 



Granite (Pieton) 



Major unconformity 



Granite gneiss 



Grenville 



X. — Van Hise am 
1 and Barrett, Jour! 
is, Geol. Survey of 
f c ?ht, Ont. Bur. Min 

anurn. Sci., vol. 39, p- Dept ' Geol., Univ. Calif., Vol. 10, No. 1 



CORRELATION OF THE PRE-CAMBKIAN ON THE BASIS OF TWO AND ONLY TWO GRANITIC INVASIONS 











NORTHWEST OP 


LAKE SUPERIOB 






SOUTH OF LA 


KE SUPERIOR 




NORTH OF LAKE HURON 


SOUTHEASTERN DISTRICTS 








I 


„ 


ni 


IV 




VI 


VII 


Cbystal- Falls 




i 






im 


B E^a-o 


XV 






Keweesawam 
(Epoch, Series) 


Dykes 




Kewecuawan 


Koweonawan 


Kewecuawan 




Keweenawan 








DykeB 


Dykes and Laccolith 


Silti 






i 




Aniuikian 
(Epoch, Buries) 






Slates, iron formation, 
quartzito 


Animikian 

Rove slate, iron 
formation 


Animikian 

Rove- slate, iron 


A,„,„,k»„ 

Virginia slate, Biunbik L F. 
Pokegame quartzite 


'""opps Formation 
Slate, pfraywarkc, 
chert, conglomerate 


Mil liig;immo slate 




Volcuuies, Michigan, me 
Blate, Bijiki L F-, 
Goodrich quartzite 


Cobalt Series 


Cobalt Series 


Cobalt Series 






biUBUN Interval 


Major unconformity 


Major unconformity 


Major unconformity 




Major unconformity 


Jfajor unconformity 


Major unconformity 


Pnronformirjf 




Pnconrorm.Iy 


Major unconformity 


Major unconformity 


Major unconformity 








" Revolution" 


Granite, syenite etc 


Granite gneiss 






Granite (Giants Range) 


Granite (Giaots Range) 


Granite [Prosquo Isle) 


Granite 




Granite (Killaraoy) 


Granite gneiss 


Granite (Lorrain) 


Granite (Moira) 


Granite (Picton) 




? 

Il 

1 i 


Tf.UISKAUIAN 

(Epoch, Series) 


Seine Series 

Slate, quartzite, 


Slate, quartzite, co-i^lomi-nitc, 


Graywarko, elate 


Grnywacke 


Knife Lake slate, 
A gown I. P., 


Slate, crnywacko, 
conglomerate 


Tyler slate, volcanies, 
Ironwood I. F., Palms 


Paint slate, lavas, Hnnbury 
slate, Vulcan I. F., Ajibik 
quartzito, Hemlock volcanies 


Qninnesec schist, Hanburj 
Slate, Vulcan L F-, 
quartzite 


Negauneo I. F., Siamo 
slate, Ajibik quartzito 








gs 










Unconformity 










Unconformity 


Unconformity 


Unconformity 


Unconformity 


Unconformity 










i 
I 




Bruce 

(Epoch, Series) 




Steoprock Series 

quartzite, conglomerate 










Sunday quartzito 


Randvillo dolomite, 
Sturgeon quartzite 


Quartzite 

Bandvilln dolomite, 
Sturgeon quartzite 


We we slate, 
Mesnatil quartzito 


Bruce Scries 

gray wacko, limestone, 
conglomerate, quartzite 












Ephaubentia!; Interval 


Major miron/orm-ty 


Major unconformity 


Major unconformity 


Majnr unconformity 


Major unconformity 


Major unconformity 


afajorunconformiij/ 


Major unconformity 


ifajorurrcoii/ormitu 


Major unconformity 


Mo/orHneon/ormitj, 


If ajor unconformity 


Major unconformity 


Major unconformity 


Major unconformity 


5 


Laubentiaj) B evolution* 


Granite gneiss 


Granite gneiss 




Granite gneiss 


Granite gneiss 


Granite 


Granite gneiss 


Granite gneiss 


Granite gneiss 


— 




Granltef 


Granite gneiss 








If 


Geenvtlle 

(Epoch, Series) 
























Grenville 




Grenville 






§| 
o -S 


Keewatin 
(Epoch, Series) 




Keewatin 


Keewatin 


Keewatin 


Keewatin 


Keewatin 


Keewatin 




Keewatin 


Keewatin 


Keewatin 


Keewatin 


Keewatin 


Keewatin 








Coutchicihno 
(Epoch, Beries) 


Coutchiching 





























•Aiimi (Prablenu o( Amrricin Gmlojj. p. 63) taka ciciplion io plscinf lbs L»n«nll»n Authorities for the sequence shown in e.ich of the Columns of the tabulation: III. IV, V, VI. VII, X. — Van Uitr and L*llh. U. 8. G. S. Won, 53. 1911. t Pcbbln Id TMdiikimiin. 




1916] 



Lawson: Correlation of Pre-Cambrian Rocks 



19 



belonged to an entirely distinct era — the Archean. Its history is a 
record of physical movements which cannot be discussed in terms of 
life, and the palaeontologists should refrain from insisting on their 
nomenclature in a field in which they do no work. The labor of har- 
monizing the views of geologists who know something of this great 
field is difficult enough without having to struggle with an inappro- 
priate classification injected by those who contribute nothing to the 
solution of its problems. To me the terms Archeozoic, Early Protero- 
zoic and Late Proterozoic 3 " are meaningless and confusing. Whatever 
meaning they may have to anyone is necessarily visionary ; and I ques- 
tion the advisability of teaching visions to beginners in geology. 



so Pirsson and Sehuchert, Textbook of Geology, Pt. II, pp. 444-445, 1915. 



Transmitted March 30, 1916. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 

Vol. 10, No. 2, pp. 21-24, 1 text-figure 



Issued October 3, 1916 




$ OCT 1 31916 




A NEW MUSTELID FROM THE THOUSAND 
CREEK PLIOCENE OF NEVADA 



BY 

EMERSON M. BUTTERWORTH 



UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



Note. — The University of California Publications are offered in exchange for the publi- 
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Geology. — Andrew C. Lawson and John C. Merriam, Editors. Price, volumes 1-7, $3.50, 
volumes 8 and following, $5.00. 

Cited as Univ. Calif. Publ. Bull. Dept. Geol. 

Volume 1, 1893-1896, 435 pp., with 18 plates, price $3.50 

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A list of titles in volumes 1 to 5 will be sent upon request. 

VOLUME 6. 

1. The Condor,-like Vultures of Rancho La Brea, by Loye Holmes Miller 15e 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part I. — Geologic History 50c 

3. The Geology of the Sargent Oil Field, by William F. Jones 25c 

4. Additions to the Avifauna of the Pleistocene Deposits at Fossil Lake, Oregon, by 

Loye Holmes Miller 10c 

5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe, by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of Rancho La Brea, by John C. 

Merriam. 

7. A Collection of Mammalian Remains from Tertiary Beds on the Mohave Desert, 

by John C. Merriam. 

Nos. 6 and 7 in one cover 10c 

8. The Stratigraphic and Faunal Relations of the Martinez Formation to the Chico 

and Tejon North of Mount Diablo, by Roy E. Dickerson .... 5c 

9. Neocolemanite, a Variety of Colemanite, and Howlite from Lang, Los Angeles 

County, California, by Arthur S. Eakle. .• 10c 

10. A New Antelope from the Pleistocene of Rancho La Brea, by Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part II. — Vertebrate Faunas 1.00 

12. A Series of Eagle Tarsi from the Pleistocene of Rancho La Brea, by Loye Holmes 

Miller _ 10c 

13. Notes on the Relationships of the Marine Saurian Fauna Described from the Triassic 

of Spitzbergen by Wiman, by John C. Merriam. 

14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13 and 14 in one cover 15o 

15. Notes on the Later Cenozoic History of the Mohave Desert Region in Southeastern 

California, by Charles Laurence Baker 50c 

16. Avifauna of the Pleistocene Cave Deposits of California, by Loye Holmes Miller .... 15c 

17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5c 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25c 



VOLUME 7. 

1. The Minerals of Tonopah, Nevada, by Arthur S. Eakle 25c 

2. Pseudostratification in Santa Barbara County, California, by George Davis Louder\ 

back , 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Rancho La Brea, by John C. 

Merriam 5c 

4. The Neocene Section at Kirker Pass oh the North Side of Mount Diablo, by Bruce > 

L. Clark 1 ~ 15c 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60c 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 

Vol. 10, No. 2, pp. 21-24, 1 text-figure 



Issued October 3, 1W6^ 011 



A NEW MUSTELID FROM THE THOUSAND 
GREEK PLIOCENE OF NEVADA 



BY 



EMERSON M. BUTTER WORTH 



The collections made by the University of California expedition to 
the Thousand Creek region of Nevada in the summer of 1915 include 
a mustelid form differing markedly from previously known types. 
It is desirable to place on record a description of this addition to the 
Great Basin fauna in order that the information may be available 
for studies involving the whole faunal assemblage of the Thousand 
Creek Pliocene. 

The writer wishes to express his appreciation for the kind criticism 
and guidance of Professor John C. Merriam, under whose direction 
this work has been executed. 

Taxidea nevadensis, n.sp. 

Type specimen an imperfectly preserved mandible, with P 4 , M„ and M 2 ; 
no. 22290, Univ. Calif. Col. Vert. Palae.; from the Thousand Creek Pliocene of 
Thousand Creek, Nevada. 

Diagnostic characters: teeth robust, P 4 with accessory cusp posterior and 
external to the protoconid; protoconid, paraeonid, and metaconid of M, forming 
an approximately equilateral triangle, with the cutting shear poorly developed; 
heel of Mj large, with peg-like hypoconid, and well-developed entoconid; M 2 
nearly circular in cross-section, but with four imperfectly developed tubercles. 

The new mustelid form is known by a single mandible, specimen 
22290, representing an animal intermediate in size between the Recent 
badgers and the martens. Due to the fragmentary nature of the 
material, discussion of generic and specific characters must be con- 
fined to the dentition. Imperfect preservation also precludes the 



22 



University of California Publications in Geology [Vol. 10 



submission of any but inferential data regarding the teeth anterior 
to P 4 . 

Judging from the crowding of the entire dentition anteroposteri- 
orly and the difference in size between the root of P 4 and the alveolus 
of P.,, it is to be assumed that the premolars of specimen 22290 have 
suffered reduction in number and dimensions, consisting in part in the 
elimination of P^ 

P 4 , the sole complete representative of the premolar series, is robust 
and possesses a cusp posterior and external to the protoconid. This 
cusp is prominent in the Procyonidae and other carnivore phyla, but 
seems to reach its highest development in the mustelid genera Maries 
and Taxidea. 




Fig. 1. Taxidea nevadensis, n. sp. Type specimen, no. 22290, X 2. Outer 
and occlusal views of lower dentition. Thousand Creek beds, Thousand Creek, 
Nevada. 

Mi is heavy and possesses a rudimentary shear. The paraconid 
and protoconid are of equal size, and with the slightly smaller meta- 
conid form an approximately equilateral triangle. The paraconid is 
clearly mediad of the median anteroposterior line of the tooth. The 
heel of M 1 is larger than that observed in any of the described mustelid 
forms with the exception of Meles, the Old World badger. The heel 
is somewhat trilobate in form. The hypoconid and entoconid are 
exceptionally well developed, and the posterior region is elevated to 
form a horseshoe-shaped ridge. 

M 2 is nearly circular in cross-section, and probably single-rooted. 
It is inserted at an angle of about 15° to the occlusal surface of the 
heel of the carnassial, bringing its crushing face mediad of the median 
anteroposterior line of the dentition. This character is possibly at- 
tributable to individual variation. The crushing surface of the tooth 



1916] 



Butterworth: A New Mustelid 



23 



is basin-like and irregularly cuspate around the periphery, with the 
protoconid, metaconid, hypoeonid, and entoconid faintly defined. 

The unmistakable differences presented by the second lower molar 
are sufficient to separate the new mustelid from the Procyonidae, the 
only other phylum of the Carnivora possessing characters close enough 
to justify comparison. Though there can be no question as to its 
mustelid affinities, the Thousand Creek form seems markedly different 
from any other representative of the group. Resembling the modern 
badgers in its generic characters, specimen 22290 shows the following 
noteworthy contrasts to the Recent Taxidea taxxis neglecta of North 
America: (1) The heel of M 1 of the Thousand Creek form is rela- 
tively larger in every dimension than the heel of this tooth in Taxidea. 
(2) In Taxidea the tubercles of the heel are much more highly speci- 
alized for a cutting function. (3) In Taxidea the metaconid is slightly 
less prominent and is posterior to the protoconid, while the metaconid 
of the fossil tooth is located nearly as far forward as the protoconid. 
The general structure of the carnassial is, however, much alike in the 
two forms, and the structure of the last premolar is identical. 

Fundamental differences exist between the fossil mustelid and 
Meles. The simple spike-like P 4 of the Old World badger is in marked 
contrast to the bicuspate P 4 of the form from the Thousand Creek. 
The former has the cutting shear of the carnassial well developed, the 
latter exhibits a more primitive structure of this part of the tooth. 
In Meles the metaconid of M 1 is situated far posterior to the proto- 
conid and the markedly basin-like heel is cuspate only around the 
border of the tooth, while the metaconid of the fossil tooth is located 
almost as far forward as the protoconid, and the heel has no pro- 
nounced basin. 

Lutra, Lutreola, and Mephitis possess dental characters widely 
divergent from those of the Thousand Creek mustelid. These char- 
acters preclude any possibility of close relationship to the form under 
discussion. 

The fossil form resembles Taxidea in the structure of the lower 
carnassial and of P 4 , though there occur notable differences of pro- 
portions. It resembles Meles in the ratio between the heel dimensions 
and the anterior portion or triangle of the carnassial, but differs from 
the latter form in the conformation of the heel of this tooth and also 
in respect to the number of cusps of P 4 . 

It is evident that the Thousand Creek form is more closely related 
to Taxidea than to Meles, as differences of structure are of higher rank 



24 



University of California Publications in Geology [Vol. 10 



than differences of proportion. This conclusion is consistent with the 
evidence of geographical distribution. Meles is an Old World type ; 
Taxidea, a genus characteristic of the New World, is found living in 
the region where the fossil form occurs. While the structure of the 
specimen from the Thousand Creek shows close relationship to Taxidea, 
the difference existing in the conformation and proportions of the 
heel of Mi indicate that the fossil form represents a group distinct 
from the modern American badgers. While it is probable that a new 
group of at least subgeneric value has been here described, definite 
classification must await more complete structural representation. 



Measurements 



T. neva- 



densis 



Type 

specimen, T. taxus (a) M. taxus (6) 
Thousand Recent, Recent, 



Creek California Germany 



Length anterior side P + to posterior side M. 

P 4 , anteroposterior diameter 

M,, anteroposterior diameter 

Mi, transverse diameter at protoconid 

M u anteroposterior diameter of heel 

Mi, transverse diameter of heel 



18.5 mm. 29 29 

6 9 7.1 

9.5 14 16 

5 6 5.5 

5 5 7 

4.5 6.2 7 



(a) 4937 Mus. Vert. Zool. 

(b) 21980 Mus. Vert. Zool. 



Transmitted March 10, 1916. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 3, pp. 25-37, 10 text-figures Issue 




THE OCCURRENCE OF ORE ON THE LIME- 
STONE SIDE OF GARNET ZONES 



BY 

JOSEPH B. UMPLEBY 



UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



Note. — The University of California Publications are offered in exchange for the publi- 
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Department. University Library, Berkeley, California, U. S. A. 

Otto Harrassowitz • R. Friedlaender & Sohn 
Leipzig Berlin 
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Geology. — Andrew C. Lawson and John C. Merriam, Editors. Price, volumes 1-7, $3.50, 

volumes 8 and following, $5.00. 

Cited as Univ. Calif. Publ. Bull. Dept. Geol. 

Volume 1, 1893-1896, 435 pp., with 18 plates, price _ $3.50 

Volume 2, 1896-1902, 457 pp., with 17 plates and 1 map, price $3.50 

Volume 3, 1902-1904, 482 pp., with 51 plates, price $3.50 

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Volume 5, 1906-1910, 458 pp., with 42 plates, price $3.50 

A list of titles in volumes 1 to 5 will be sent upon request. 



VOLUME 6. 

1. The Condor-like Vultures of Raneho La Brea, by Loye Holmes Miller 15« 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part I. — Geologic History 50c 

3. The Geology of the Sargent Oil Field, by William F. Jones 25c 

4. Additions to the Avifauna of the Pleistocene Deposits at Fossil Lake, Oregon, by 

Loye Holmes Miller 10c 

5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe, by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of Bancho La Brea, by John C. 

Merriam. i 

7. A Collection of Mammalian Remains from Tertiary Beds on the Mohave Desert, 

by John C. Merriam. 

Nos. 6 and 7 in one cover 10c 

8. The Stratigraphic and i'aunal Relations of the Martinez Formation to the Chico 

and Tejon North of Mount Diablo, by Roy E. Dickerson 5c 

9. Neocolemanite, a Variety of Colemanite, and Howlite from Lang, Los Angeles 

County, California, by Arthur S. Eakle 10c 

10. A New Antelope from the Pleistocene of Raneho La Brea, by "Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part II. — Vertebrate Faunas 1.00 

12. A Series of Eagle Tarsi from the Pleistocene of Rancho La Brea, by Loye Holmes 

Miller _ 10c 

13. Notes on the Relationships of the Marine Saurian Fauna Described from the Triassic 

of Spitzbergen by Wiman, by John C. Merriam. 

14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13 and 14 in one cover I5o 

15. Notes on the Later Cenozoic History of the Mohave Desert Region in Southeastern 

California, by Charles Laurence Baker 50c 

16. Avifauna of the Pleistocene Cave Deposits of California, by Loye Holmes Miller .... 15c 

17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5c 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25c 



VOLUME 7. 

1. The Minerals of Tonopah, Nevada, by Arthur S. Eakle 25c 

2. Pseudostratification in Santa Barbara County, California, by George Davis Louder- 

back 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Raneho La Brea, by John C. . 

Merriam 5c 

4. The Neocene Section at Kirker Pass on; the North Side of Mount Diablo, by Bruce 

L. Clark 15c 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60c 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 3, pp. 25-37, 10 text-figures IssueO^t^f^JV^} 

— f& 

W OCT 2 1 1916 * 

THE OCCURRENCE OF ORE ON THJT-fcB^ 
STONE SIDE OF GARNET ZONES* 

BY 

JOSEPH B. UMPLEBY 



CONTENTS 

PAGE 



Introduction 25 

Statement of Thesis 26 

Examples 26 

Washington Camp, Arizona 26 

Silverbell, Arizona 27 

Seven Devils, Idaho 28 

Velardefia, Mexico 20 

Dolores Mine, Mexico 31 

Mackay, Idaho 33 

Whitehorse Copper Belt, Yukon 33 

Interpretation 35 

Summary and Conclusions 37 



Introduction 

Contact metamorphie ore deposits comprise a type of particular 
interest because in their geologic occurrence and mineralogical makeup 
they are intermediate between normal fissure veins and magmatic 
segregations. During the last sixteen years much attention has been 
given to them by students of ore genesis and ideas concerning their 
origin have passed through many stages of development. Their general 
occurrence at or near igneous contacts affords the common ground 
that they are genetically related to intrusive masses, but concerning 
the details of this relationship wide diversity of opinion exists. Does 
the intrusion merely supply heat to the meteoric circulation, or 
does it supply the metamorphosing solutions? Is the metamorphism 

* Published by permission of the Director of the United States Geological 
Survey. 



26 University of California Publications in Geology [Vol. 10 

coincident with intrusion, or subsequent to the solidification of a 
magma shell? Does the magma supply silica, alumina and iron for 
the lime silicates, or are these concentrated from the invaded rocks 
either by a reduction in volume or by meteoric waters approaching 
the contact? Is the attack of meteoric waters on the solidified but 
still hot intrusive an important factor? Does the metasomatism proceed 
by constant volumes? Do the lime-silicates and sulphides develop 
simultaneously and have they a common source? These are the prin- 
cipal questions now under discussion. Each of them seems to have 
been answered satisfactorily for individual deposits, but the problem 
remains how far one pattern may fit the many known occurrences, and 
what factors determine diversities within the type. 

Any adequate conception of the genesis of contact deposits must 
be based on the constant relationships which they exhibit, but must 
be sufficiently elastic to allow for observed diversities. Thus, to add 
either descriptions of peculiar features of individual deposits, or to 
point out relationships so often recurring as to be scarcely fortuitous, 
is to make a contribution to our knowledge of the subject, even if the 
genetic significance be not fully comprehended or be incorrectly 
stated. 

Statement of Thesis 

This paper is an endeavor to point out a common, perhaps a 
general, spacial relationship between ore and garnet zones in the con- 
tact deposits of the North American Cordillera. It is certain that in 
many deposits the ore bodies favor the limestone rather than the 
intrusive side of the garnet zone. In several places the ore comes 
directly up to the igneous contact, but so far as is known to the writer 
no clear occurrence has been described where barren lime-silicate rock 
continues outward far beyond such ore. In the case of engulfed blocks 
of limestone which have suffered metamorphism the limestone side 
of the garnet mass is toward the central part of the block, and here 
ore is found in several localities. In some of these cases all of the 
limestone has disappeared but the ore is centrally situated. 

In the following paragraphs this relationship is pointed out in 
brief descriptions of several contact deposits, and finally its bearing 
upon modern theories is suggested. 

Examples 

Washington Camp, Arizona. — The ore deposits at Washington 
Camp occur locally on the border of a great island-like mass of lime- 



1916] TJmpleby : Ore on the Limestone Side of Garnet Zones 27 



stone surrounded by granitic rocks comprising the main part of 
Patagonia range. 1 The sedimentary beds dip and strike diversely in 
different places, but the dip is prevailingly westward at angles of 
30 to 90 degrees. The deposits are tabular replacements in limestone 
both remote from and near to the igneous contact "and have not been 
observed in any instance to extend ever so slightly into the surround- 
ing granite." The common gangue is garnet, with which the metallic 
minerals, chalcopyrite, sphalerite and to a minor extent galena, are 
intimately associated. It is particularly noteworthy, however, that 
"the ore-body accompanying a contact garnet zone is always on the 
inside of the zone, that is, between the main body of the garnet ledge 
and the limestone, and not between the garnet ledge and the granite." 2 

Crosby 3 states further that "obviously enough, the ores, as we 
now have them, are due to a metasomatie impregnation and replace- 
ment of the limestone against and in the massive garnet ledge. ' ' 

The deposits of Washington Camp, therefore, clearly exemplify 
the formation of ore on the limestone side of garnet zones. It is per- 
haps worthy of note that here there has been no endomorphism, a 
feature in which these deposits are different from several of the others 
which are described. 

Silverbell, Arizona. — In the Silverbell district is a series of lime- 
stone blocks of Paleozoic age completely surrounded by alaskite, 
alaskite porphyry, biotite granite, andesite and quartz porphyry, in- 
truded in the order named. 4 The intrusion of the alaskite porphyry 
and the biotite granite was followed by intense sericitization and 
silicification of these rocks and by the development of great masses 
of garnet, quartz and wollastonite in the adjacent limestone. "Follow- 
ing close upon these solutions came metal-bearing magmatic waters, 
which impregnated porphyry, granite and alaskite with cupriferous 
pyrite, and deposited in the garnet zones chalcopyrite and copper- 
bearing pyrite that make important bodies of contact metamorphic 
ores." Veins containing lead-silver ores also occur. Endomorphism 
is represented by a widespread silicification of the intrusions and a 
local development of garnet and epidote of igneous-rock derivation. 
The common section from the boundary of the intrusive rock to the 
limestone is "three to ten feet thick, of solid garnet and quartz, with 

i Crosby, W. O., The Limestone-granite contact-deposits of Washington 
Camp, Arizona, Trans. Am. Inst. Min. Engrs., vol. 36, pp. 626-646, 1906. 
Crosby, W. O., op. cit., p. 632. 
« Op. cit., p. 641. 

4 Stewart, C. A., The geology and ore-deposits of the Silverbell Mining 
District, Arizona, Trans. Am. Inst. Min. Engrs., vol. 43, pp. 240-290, 1912. 



28 



University of California Publications in Geology [Vol. 10 



varying amounts of wollastonite, and microscopic diopside. This is 
gradually replaced by garnet rock with veins and bunches of marble, 
and the latter becomes more abundant until we find marble with lenses 
and stringers of garnet and associated minerals, and these become 
less numerous until a pure marble remains." 5 "Parts of an ore-body 
may be one hundred feet or more from an intrusive rock; but some 
portion of every ore mass is close to the contact with one of the two 
above-named igneous rocks. Usually there is a five to ten-foot band 
of garnet rock between ore and porphyry." 6 "The ore-minerals are 
definitely later than most of the gangue-minerals, and occur com- 
monly as veinlets in the garnet-quartz-calcite mass, or disseminated 
through it," 7 

Seven Devils, Idaho. — The rocks of the Seven Devils district 
comprise slate, quartzite, limestone and a vast amount of associated 
greenstone invaded and metamorphosed by a quartz diorite phase of 
the Idaho granite and capped locally by Columbia basalt. 8 The ore 
deposits are in typical contact zones situated in part along the external 
contact of the quartz diorite but principally adjacent to engulfed 
blocks of limestone. Garnet, epidote and quartz are abundant gangue 
minerals and bornite and chalcopyrite are the principal sulphides. In 
the Queen, Blue Jacket and Arkansas mines the ore occurs on the lime- 
stone side of garnet zones across which veinlets of chalcopyrite and 
bornite in a quartz gangue connect with the igneous mass on a dip of 
about 15 degrees. Mining development along these veinlets has ceased 
in most places at the igneous contact, but they are known to extend 
locally twenty-five or thirty feet into the quartz diorite without notice- 
able diminution in size or change in character. One locality where 
the veinlets are particularly well shown and are closely spaced is in 
the Queen No. 1. Intermediate stope. See figure 1. 

In the Peacock Mine the ore occurs in the central part of a large 
garnet-epidote area bordered on the east and west by diorite and on 
the south by a green porphyritic rock believed to be an engulfed 
portion of the greenstone series. The main sedimentary contact lies 
a few hundred feet to the north across an area of normal diorite. 
Thus it is suggested that an engulfed block of limestone 'determined 

s Stewart, C. A., op. cit., p. 272. 
o Ibid., pp. 280-281. 
- Ibid., p. 282. 

s Lindgren, W., The gold and silver veins of Silver City, De Lamar and 
other mining districts in Idaho, Twentieth Ann. Kept., U. S. Geol. Survey, Pt. 
3, pp. 249-253, 1900. Umpleby, J. B., Reconnaissance examination, 1915. Re- 
port in preparation. 



1916] Umpleby: Ore on the Limestone Side of Garnet Zones 29 



the development of the garnet-epidote mass at the Peacock Mine, a 
suggestion confirmed by the occurrence of marble in diamond-drill 
cores which come from the deposit, although the location and direction 
of the hole is not known to the writer. The point of particular interest 
is that the ore-body occurs in the central part of the garnet mass. 

The Seven Devils deposits exhibit both exomorphism and endo- 
morphism, the latter being clearly shown by the stringers and replace- 
ment bodies of epidote in the diorite several feet from limestone 
contacts. 

Velarde na, Mexico. — The Velardena district is an area of folded 
Cretaceous ( "?) limestone overlain by andesitic tnft's and flows and 
traversed by andesitic dikes. The principal intrusive rocks are dikes 




SCALE Of FEET 

t 5 3a 

Fig. 1. Transverse section showing relations of ore to limestone and quartz- 
diorite in Intermediate Stope, Queen No. 1 Mine, Seven Devils, Idaho. 

and necks of alaskite and traehytic alaskite accompanied or closely 
followed by extensive injections of dioritic rocks. All of the intrusive 
rocks have caused metamorphism and at a time "definitely subsequent 
to intrusion, ' ' as shown by extensive endomorphism. The ore deposits 
are of varied character and clearly indicate successive stages of depo- 
sition. "Sulphides began to be deposited with the lime-silicates, but 
the chief sulphide deposition followed the lime-silicate period directly, 
with quartz as principal gangue. " 10 

The Copper Queen is the principal copper ore-body of the district 
and consists of three main pipes in metamorphic rock at the contact 
of the diorite intrusion. The principal sulphides are cupriferous 

11 Spurr, J. E., and Garrey, G. H., Ore-deposits of the Velardena District, 
Mexico, Econ. Geol., vol. 3, pp. 688-725, 1908. 
io Op. ext., p. 724. 



30 



University of California Publications in Geology [Vol. 10 



pyrite, sphalerite, and galena. The relation of the ore to garnet rock 
and limestone in this deposit is clearly shown by Prescott in the 
illustrations reproduced as figures 2 to 5. 11 Prescott uses these figures 
to illustrate the occurrence of ore at points where limestone projects 




INTERMEDIATE HORIZON 

Fig. 3. 



" " r s s v , v / / 
/ ✓ ✓ l/- j 

UPPER HORIZON 

Fig. 2. 




Generalized plan of ore chimney at Copper Queen Mine, Velardena, Durango, 
Mexico. After Basil Prescott, Econ. Geo!., vol. 10, p. 62, 1915. 



ii Prescott, Basil, Some observations on contact metamorphie deposits, Econ. 
Geol., vol. 10, pp. 55-69, 1915. 



1916] Umpleby: Ore on the Limestone Side of Garnet Zones 31 



into the intrusive mass, but they are also most pertinent to the present 
discussion. In figures 3 and 4 the occurrence of ore on the limestone 
side of the lime-silicate zone is evident. In figure 5 the central lime- 
stone has been changed to ore, but its former extent into the area now 
ore is clearly shown by the relations at the top and bottom of the 
figure. In figure 2 the ore occurs in the central part of a lime-silicate 
mass which in the plane of the section is surrounded by the intrusive 
rock. 

Dolores Mine, Mexico. — The Dolores Mine, near Matehuala, S. L. P., 
Mexico, is situated in an area of Mesozoic limestone, overlain by shale, 
which forms a great half-dome down faulted on the east. 12 Cutting 
the sedimentary rocks in the central part of the field are two masses 
of quartz monzonite. Both of the intrusives have caused noteworthy 
metamorphism, but about the northern, or Cabriza body, contact rock 
is especially abundant and widespread. The contacts of the intrusive 
masses are very irregular and much of the lime-silicate rock has formed 
at the expense of quartz monzonite, although perhaps most of it is 
of limestone derivation. The metamorphic minerals include pyroxene, 
garnet, vesuvianite, wollastonite, fluorite, quartz, and the metallic 
sulphides, chalcopyrite, pyrite, arsenopyrite, pyrrhotite, blende and 
galena. Cupriferous pyrite is the most important ore mineral. Careful 
study has revealed a definite sequence in mineral formation as 
follows: 13 1, aluminous pyroxenes; 2, aluminous garnet (grossularite) 
and vesuvianite; 3, wollastonite; 4, lime-iron pyroxene (hedenbergite) ; 
5, lime-iron garnet (andradite) ; 6, fluorite, quartz and metallic sul- 
phides (and actinolite and hornblende) ; 7, metallic sulphides (and 
quartz and fluorite) ; 8, calcite. As the caleite is quite certainly 
residual from the limestone, it is clear that in the Dolores deposit the 
metallic sulphides were among the last metasomatic minerals developed 
and formed later than the lime-silicates. 

The paper above cited does not describe in detail the spaeial 
relationship of the ore bodies to the limestone and monzonite, although 
it is stated that they "occur largely at the very contact, frequently 
with limestone as one wall." 14 In the paper by Prescott, 15 however, 
sketches of the ore chimney at Dolores Mine, reproduced herein as 
figures 6 to 8, are pertinent. Figures 7 and 8 are clearly illustrative 

12 Spurr, J. E., Garry, G. H., and Fenner, C. N., Study of a contact meta- 
morphic ore deposit: The Dolores Mine, at Matehuala, S. L. P., Mexico, Econ. 
Geol., vol. 7, pp. 444-484, 1912. 

13 Ibid., p. 444. 

14 Ibid., p. 446. 

i ■> Op. cit., p. 65. 



32 



University of California Publications in Geology 



[Vol. 10 




UPPER HORIZON. 

Fig. 6 




INTERMEDIATE HORIZON. 




DEEP HORIZON. 
PiiT. 8 



LIME 31 



CONTACT 
METAMORPHIC ROCK 



77777 



Generalized plans of ore chimney at Dolores Mine, Matehuala, San Luis 
Potosi, Mexico. After Basil Preseott, Econ. Geol., vol. 10, p. 65, 1915. 



1916] Umpleby: Ore on the Limestone Side of Garnet Zones 33 



of the occurrence of ore on the limestone side of garnet zones. The 
relations shown in figure 6 do not support the general idea, but it is 
introduced because it represents a part of the same chimney of ore 
shown in the other two figures and has value as a check to sweeping 
generalizations. Within the area represented by it the writer would 
expect to find clear evidence of replacement of the silicates by the 
sulphides. 

Mackay, Idaho. — The contact metamorphie copper deposits at 
Mackay, Idaho, occur well within a mass of granite porphyry which 
has invaded folded strata of Carboniferous age. 10 Several engulfed 
blocks of limestone occur in the vicinity of the ore deposits and have 
been variously metamorphosed so that some are bordered by only a 
narrow margin of marble, others are more than half changed to lime- 
silicate rock, and still others are completely transformed to garnet- 
diopside rock and ore. Marmorization accompanied intrusion but 
the intense metasomatism followed the fracturing of a thick magma 
shell. In many places the granite porphyry bordering included lime- 
stone masses is extensively changed to garnet-diopside rock. 

The ore in the Copper Bullion Mine occurs along the margins of 
a block of limestone several hundred feet long and is separated from 
the granite porphyry by a zone of garnet-diopside rock from three 
or four to more than twenty-five feet wide. Marble forms the other 
wall, but this gives way within a few feet to normal limestone. The 
relations are illustrated in figure 9. 

The Alberta ore bodies, situated along a pronounced fault which 
traverses the igneous mass, comprise two groups of branching 
chimneys which occur in the central parts of large garnet areas (fig. 
10). Here no central limestone body remains, and the occurrence 
is interpreted as representing the limiting stage of ore deposition on 
the limestone side of a garnet zone which surrounds an engulfed block. 
A study of the ores shows that the sulphides locally are contempo- 
raneous with the garnet crystals but that most of them are of distinctly 
later development. 

Whitehorse Copper Belt, Yukon. — The rocks of the Whitehorse 
district comprise Carboniferous limestone largely destroyed by three 
distinct igneous invasions, the principal of which, though of variable 
composition, is predominantly hornblende granite. 17 The larger 

is Umpleby, J. B., The genesis of the Mackay Copper Deposits, Idaho, Eeon. 
Geol., vol. 9, pp. 307-358, 1914. The ore deposits of the Mackay Region, 
Idaho, Prof. Paper, U. S. Geol. Survey (in preparation). 

1 7 McConnell, R. G., The Whitehorse Copper Belt, Yukon Territory, Can. 
Geol. Survey, No. 1050, 63 pp., 2 pis., 2 figs., 8 maps, 1909. 



34 



University of California Publications in Geology 



[Vol. 10 




1916] Umpleby: Ore on the Limestone Side of Garnet Zones 35 

ore-bodies occur in the limestone close to or adjoining the granite, but 
ore also occurs in the granite, "often at considerable distance from 
the limestone." "The constituent minerals, and general character of 
the ore-bodies in the two formations, are very similar. ' ' The principal 
copper minerals are bornite and chalcopyrite, which are associated 
either with magnetite and hematite or with garnet, augite and tremo- 
lite. "All the ore-bodies of this (the latter) class, so far discovered, 
occur in the limestone, close to the granite, and are often separated 
from the granite by a zone of more or less completely replaced lime- 




Fig. 10. Section through Alberta Mine, Mackay, Idaho, showing occurrence 
of ore in the central part of a garnet-diopside mass. 

stone." 18 This relationship is clearly brought out by the geologic 
maps of the Grafter Mine and the Best Chance ore-body. Endo- 
morphism has resulted in a considerable development of garnet, 
pyroxene and epidote in the granitic mass. 

Interpretation 

The extent to which the occurrence of ore on the limestone side 
of garnet zones, as illustrated in the seven well known districts cited 
above, represents a general law cannot be definitely stated at present. 
Indeed, the object of this paper is merely to set it forth as a working 
hypothesis in the hope of arousing discussion and stimulating obser- 
vation. It is highly probable, however, that there are many more 
examples of the relationship. In papers on four of the districts cited 
one writer has clearly stated or illustrated the relationship, but in the 
writing of another on the same deposit I have been unable to find 
a quotable statement. 

The occurrence of ore on the limestone side of garnet zones, 
whether it be a constant relationship or not, must be explained for 



is ibid., p. 22. 



36 



University of California Publications in Geology [Vol. 10 



the several important deposits cited above before knowledge of ore 
genesis approaches completeness. In the abstract there are two 
possible explanations; (1) either the sulphides form synchronously 
at a lower temperature than the lime-silicates and thus occur near the 
outer margin of metamorphism. or (2) the sulphide-rich solutions are 
delivered to the contact zone later than those characteristically forming 
lime-silicates, and replace the limestone in preference to the meta- 
morphic rock earlier developed. Probably most students of the subject 
will favor the latter view and in stong support of it is the occurrence 
of apparent feeders at Seven Devils which connect the ore downward 
across the garnet zone with the quartz diorite. Also in support of 
this alternative is the broad observation based on mineral paragenesis 
"that emanation of sulphides and magnetite continues after the con- 
tact action, resulting in silicate rock, is completed." 18 

But the alternative explanation must not be too lightly considered. 
If the sulphides form at lower temperatures than the lime-silicates, 
their zone of deposition may be expected gradually to draw in toward 
the source of energy as cooling of the intrusive mass progresses. This 
implies a superposition of minerals of lower temperature range upon 
those earlier formed at higher temperatures, providing that their 
source of supply is not earlier cut off or exhausted. AVould not this 
give the same relations of sulphides to silicates a.s would a sequential 
supply of solutions of different type? 

It seems to the writer that the explanation of the phenomena 
requires broader considerations than the paragenetic relations of 
minerals in the hand specimen, although these have their value. It 
is generally recognized that the sulphides in part, perhaps in large 
part, develop contemporaneously with lime-silicates and that most of 
them occur in small amounts as constituents of igneous rocks. Thus, 
we would not expect to find a temperature control sufficiently marked 
to afford the relations observed in the deposits herein cited. The fact 
that the silicate minerals in most places are more widely distributed 
along the contact than the ore minerals is also probably significant. 20 
But the silicate minerals themselves are localized along the contact 
in many places and this has been considered as indicating the escape 
of the solutions through fissures in an outer magma shell.- 1 The par- 

i9 Lindgren, W., The origin of the "Garnet Zone" and associated ore 
deposits, Econ. Geol., vol. 9, pp. 283-292, 1914. 
=o Lindgren, W., loc. cit., pp. 285-286. 

2i Butler, B. S., Geology and ore deposits of the San Francisco and adjacent 
districts, Utah, Prof. Paper, U. S. Geol. Survey, no. 80, p. 12, 1913. 



1916] Umpleby: Ore on the Limestone Side of Garnet Zones 



37 



ticular localization of the sulphide-bearing portions of the contact 
zones seem to be more rationally explained by solutions of different 
or gradually changing composition than by temperature control. 

Summary and Conclusions 

The preference of ore for the limestone side of seven important 
contact zones has been shown by citations and diagrams, and a desire 
has been expressed to ascertain through discussion how general this 
relationship is. 

The phenomena may be interpreted as due either to heat control 
or to a supply of solutions of changing composition such that lime- 
silicates are predominantly formed during the earlier stages of depo- 
sition and the sulphides during the later. The latter view is favored 
by the writer. 

If the relationship should prove to be a constant one it will be 
of considerable value in the exploitation of contact deposits, for other 
things being equal, development work will follow the limestone rather 
than the intrusive side of the garnet zone. Even at present enough 
is known to recommend that the habit of the individual deposit in 
this particular be carefully observed as a guide to later search for 
ore. In the case of engulfed blocks of limestone the limestone-side 
will in many places be the central part of the garnet mass. 

Transmitted May t, 1016. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

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Vol. 10, No. 4, pp. 39-62, plates 1-2 Issued October 1 1, 1916 



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Sal IVIuse^ 



FAUNA OF THE FERNANDO OF 
LOS ANGELES 



BY 

CLARENCE L. MOODY 



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Vol. 10, No. 4, pp. 39-62, plates 1-2 Issued Octobel^l, fiffe^ 2 1 1916 £ 



/0 nal Museu^, 



FAUNA OF THE FERNANDO OF LOS ANGELES 



BY 

CLAKENCE L. MOODY 



CONTENTS 

PAGE 

Introduction 39 

Occurrence 40 

Previous knowledge of related occurrences 40 

List of species 42 

Faunal summary 46 

General features of the fauna 46 

Comparison with related faunas 48 

Description of species 51 

Epitonium (Opalia) retiporosa Carpenter 51 

Siphonalia gilberti, n.sp 51 

Chrysodomus dims meridiei, n.var 52 

Trophon raymondi, n.sp 53 

Columbella constantia, n.sp 53 

Tunis (Drillia) modestus, n.sp 54 

Borsonia inculta, n.sp 54 

Mangilia muricidea, n.sp 55 

Cancellaria quadrata, n.sp 56 

Pecten (Propeamusium) levis, n.sp 56 

Macrocallista densa, n.sp 58 

Corbula tenuis, n.sp 59 

Introduction 

In the course of excavation work on Fourth Street, Los Angeles, 
in the fall of 1913, fossil-bearing beds were encountered which have 
yielded a marine fauna possessing several features that may prove 
of some importance in the final solution of the problem of late 
Tertiary history of the southern Coast Ranges of California. Mr. 
J. Z. Gilbert, of the Los Angeles High School, learned of the dis- 
covery of shells by the workmen, and took steps to secure such 
specimens as were available. Due to his painstaking and systematic 



40 



University of California Publications in Geology [Vol. 10 



collecting a fauna of approximately 160 species was obtained. The 
material, which is in a splendid state of preservation, was entrusted 
to the University of California for study. 

It is with pleasure that the writer acknowledges his indebtedness 
to Mr. Gilbert for his generosity in providing the abundant material 
for study, and to Professor J. C. Merriam and Dr. B. L. Clark for 
co-operation and valuable assistance during the progress of the work. 
This opportunity is also taken to thank Mrs. Ida Oldroyd for consul- 
tation, Dr. Paul Bartsch, Dr. Ralph Arnold and Mr. Homer Hamlin for 
information which has aided materially in the course of the study, 
and Professor W. J. Raymond for access to his splendid molluscan 
collection. 

Occurrence 

The fauna upon which the following report is based was obtained 
from a bluish gray clay exposed by excavation for a building site on 
Fourth Street between Hill Street and Broadway, near the center of 
the city of Los Angeles. Shells were first found at thirty-four feet 
from the surface. A communication from Mr. Gilbert states that the 
clays seemed to dip a few degrees toward the northwest. 

In the geologic map of the Los Angeles oil fields accompanying 
the text of Bulletin 309 of the United States Geological Survey, the 
locality under consideration is included in the Fernando formation. 
It is also stated in this bulletin 1 that marine Pleistocene deposits 
overlie the true Fernando in the region of the oil belt and farther 
south, especially on the top of the ridge on which the Normal School 
is situated. As the locality described is now inaccessible, question 
arises whether the fossils under discussion were obtained from these 
terrace deposits or from the true Fernando. From a consideration 
of various phases of the fauna to be discussed later, no hesitation is 
felt in assigning it to the latter formation. 

Previous Knowledge op Related Occurrences 
Fossils have been known from various localities in Los Angeles 
since the opening of the oil fields in and around the city. In Bulletin 
11 of the California State Mining Bureau, 1896, W. L. Watts 2 gives 
a list of 34 species obtained from oil wells and from the site of the 
State Normal School on Fifth Street, which present a faunal facies 
not different from those obtained from the Fourth Street locality. In 

1 Arnold, E., Bull. IT. S. Geol. Surv., no. 309, p. 153, 1907. 

2 Watts, W. L., Bull. Calif. State Min. Bureau, no. 11, pp. 79-81, 1896. 



1916] Moody: Fauna of the Fernando of Los Angeles 41 



the collection obtained by Mr. Wat 
following species: 

Bittium asperum Gahb 
Calliostoma eostatum Martyn 
Caneellaria vetusta Gabb 
Cerithidea californica Hald. 
Chama exogyra Conr.* 
Corbula luteola Opr. 
Crepidula grandis Conr.* 
Cryptomya californica Conr. 
Cypricardia pedroana Conr. 
Diplodonta orbella Old. 
Glycimeris (Axinaea) intermedia 
Brod. 

Kellia suborbicularis Mont. 
Lithophagus plumulus Eve. 
Macoma inquinata Desh. 
Maeoma nasuta Conr. 
Mangilia (Clathurella) conradiana 
Gabb* 

* Species known also in the Fourth i 



s, Dr. J. G. Cooper identified the 



Maetra (Standella) californica Conr. 

Mitra maura Swains.* 

Murex (Ocinebra) lurida Midd.* 

Nassa californica Conr.* 

Nassa fossata Gld.* 

Nassa mendica Gld.* 

Nassa perpinguis lids.* 

Ostrea vespertina Conr. 

Paphia staleyi Gabb 

Pecten (Janira) bellus Conr. 

Pecten (Hinnites) giganteus Gray* 

Pecten pedroanus Trask 

Plaeunanomia, n.sp. 

Platyodon cancellatus Conr. 

Saxidomus gibbosus Gabb 

Semele decisa Conr. 

Sinum (Sigaretus) planicostum Gabb 

reet fauna. 



In the above list of species ten forms are found which also occur 
in the Fourth Street fauna. 

During the construction of the Third Street tunnel fossiliferous 
blue clays were found which yielded several interesting invertebrate 
species, among which was a giant Lima described by Dr. W. H. Dall 3 
as L. hamlini. Another form which occasioned some confusion for 
a time was considered by Dr. R. E. C. Stearns 4 to belong to the 
Rudistae and was described by him as Radiolites hamlini. Upon the 
evidence of this species the deposits underlying Los Angeles were 
referred to the Cretaceous. 5 Later Dr. T. W. Vaughan expressed the 
opinion that the flat valve of the supposed Radiolites was really an 
individual coral, while the elongated portion, though still somewhat 
problematical, is probably to be referred to the Cirripedia. 6 

From a small molluscan fauna in material furnished by Dr. Stearns 
and Mr. Homer Hamlin, Dr. Dall 7 determined the Third Street tunnel 
horizon as probably Pliocene, and in 1907 Dr. Ralph Arnold 8 definitely 

3 Dall, W. II., Nautilus, vol. 14, no. 2, pp. 15-16, June, 1900. 
* Stearns, Dr. E. E. C, Science, n. s. vol. 12, no. 294, pp. 247-250, Aug. 17, 
1900. 

s Vaughan, T. W., Nautilus, vol. 14, no. 2, p. 36, June, 1900. 

e Dall, W. H., Science, n. s. vol. 15, no. 366, pp. 5-16, Jan. 3, 1902. 

~ Dall, W. H., op. cit. 

s Arnold, E., Proc. U. S. Nat. Mus., vol. 32, p. 527, 1907. 



42 



University of California Publications in Geology [Vol. 10 



correlated the Los Angeles clays with the middle Fernando formation. 
Dr Arnold regards the beds as of lower or middle Pliocene age. 9 

The species upon which this correlation was based are as follows : 

Area multicostata Sby. Pecten pedroanus Trask (abundant) 

Astarte, sp. Pecten stearnsii Dall 

Carditoid Buccinum, sp. indet. 

Lima liamlini Dall Fissuridea murina Cpr. 

Macoma, sp. indet. Neverita recluziana Petit 

Nassa hamlini Arnold Pleurotoma, sp. indet. 

Pecten ashleyi Arnold Priene oregenensis Eedf. var. 

Pecten latiauritus Conrad angelensis Arnold 

Pecten opuntia Dall ! 

Pecten opuntia, Fissuridea murina and Neverita recluziana occur 
also in the fauna from the Fourth Street locality. 

It is believed that the fossils obtained by Mr. Gilbert support this 
correlation in part, and that in addition to increasing considerably 
the known fauna of the Fernando, they present the opportunity of 
making a more exact comparison of the southern Pliocene with that 
of the Great Valley and of central California. 

List op Species 

In the succeeding faunal list a rough statement of the frequency 
value of each species is attempted by an arbitrary division of the fauna 
into four classes which are enumerated and designated as follows : 
(1) very abundant ; (2) common; (3) uncommon; (4) rare. Forms 
represented by more than twenty-five individuals have been classed 
as ' ' very abundant ' ' ; those which appear in only one or two individuals 
are "rare." In the column headed "Geologic Range," R indicates 
Recent ; PI, Pleistocene ; P, Pliocene ; M, Miocene. The ranges given 
are those heretofore recognized. 

RHIZOPODA Frequency Range 

Nodosaria, sp 4 

Anthozoa 

Astrangia insignifica Nomland 4 P 

Bryozoa 

Several species 1 

Brachiopoda 

Terebratalia hemphilli(?) Dall 4 P 

Laqueus jeffreysi( ?) Dall 4 P-E 

Amphineura 

Chiton i 4 

o Arnold, K,, Prof. Paper, U. S. Geol. Surv., no. 47, p. 29, 1906. 



1916] Moody: Fauna of the Fernando of Los Angeles 



4:; 



ASTROPODA 


Frequency 


Geol. 

Range 


Ac ma ea in sessa Hinds 


4 


Pl-R 


A o m q pa fif ao a \ \ t"i "NT ntf 'l 11 


4 


Pl-R 


A I'lmpfp tyvQ f*t It nv I ( ,, iT"iipnt'PT^ 


1 


P-R 


A in n 1 1 li n p ;i fiiTnflnfl i (, *i vnfln f at i 


4 


Pl-R 


\ in ph issa co mi °a tii ( .R ec vg ) 


1 


P-R 


A m n In qqp v p t*q t p nl n t* Tj *a 1 1 


2 


Pl-R 


A "jtl'^PQ QY1 


4 




A ot*i*si pn 1 7i on n nip fn/fo i*T"\7"n ^ 


4 


Pl-R 


T"i P 1 ' I Tl / 1 1 ( ' IT I * 1 I 4 <"t 1 1 1 J 1 


2 


P-R 


~Rpl n ssi n p.t".sj ptyi nni pq p A mold 


o 


PI 


i ttinni o Q 1 ifnTTii *»n Tn T"l nil n n il T-l n ft ep li 
U 11 U. ii i L illllUI Jl 1 (_ Hill ±J a 11 tl 11 1.1 J-Jcil Loi-'Il 


•> 


Pl-R 


1 i~ i tt tt i T'li rrn tn ill C\ *.i r tipti ■for* 


4 


P-R 


Borsonia in cults n sp 


4 


P 


C alii o stoma eanaliculatum ( JVXartyn) 


3 


P-R 


f*Q 111 Q^nYTI £1 (CPT11 Til 111 9 Til Til 1 1'T 1 P Tl i" PI" 
v^ctllloUUlilcl g tr 11 1 1 11 U 1 < t I 11 111 Vjdl JL/CJJl LCI 


3 


P-R 


liiilli ndt.nTYifl t r i (* nl ni' Tt n Vili 


2 


P-R 


Calyptra ea (Gale r us) 1113 111 miliar is ( B rod Grip ) 


2 


P-R 


rialvntfa ag vn d i :i n y T 1*1 m a T/*lr 


2 


P-R 


1 1 51 Tl P pi I SI "PI SI Crfl WTlll'M lillTil Il'lll 


4 


Pl-R 


(IflTi ppIIq tisi nnfl fiTQ n qti 


4 


p 


II pti t\Tn DTisis f".n rSPTpnlsiT*si (ihttipti'^pt 


3 


Pl-R 


Chrysodoinus dims meridici var nov 


4 


P 


(jliwsndnTiiiis ppf*t".TrnKt".T*i h ( *n 7*1 ipn tpt* 


■i 


Pl-R 


Chrysodomus tabulatus Baird 


3 


P-R 


lifilnTTiTiPllsi n 1 1 "Pni'ii 1 n 11 RlrniTt 


o 


Pl-R 


Columbella (Astvris) cftrinntft Hinds 


1 


P-R 


Columbella (Astyris) constantia n sp 


2 


p 


Columbella (Astyris) g*ausapata, Gould 


1 


P-R 


Columbella (Astyris ) tuberosa ( G3.rp6D.tGr) 


1 


P-R 


11 u s c a 1 i fo r n ic u s IT i 11 d s 


2 


P-R 


Crepidula a dune a Sower by 


3 


P-R 


CrGpidula dorsata Broderip 


4 


P-R 


Crepidula rand is ]\Iiddendorf 


3 


M-R 


CrGpidula nivGa Da 11 


4 


P-R 


C\ vpni (\ 11 1 m riTTTi ptis nnriTfl^ 


4 


P— R 


li PATii fin la rn (rn^i TSTn 1 1 n 1 1 


4 


Pl-T? 


fivl i pTitis n 11 ) n Rvnwn 


3 


Pl-R 


"Fin i ton i n m hind si ( C\ n rnpn fpr "i 


3 


Pl-R 


Epitonium in dian orum ( CarpGn ter ) 


3 


Pl-R 


rlllltfiTlinTii ^OtiiIii ^ ppfiTinrAfld ^ Pivnpnf 

XJ^Tl LU111LIII1 ^ \J 1 la IltX ) 1 C L1UUJ Uftcl I \JCbL UglL bCl J 


4. 


R 


Fissuridea murin a ( Carpenter) 


4 


P-R 


Fn si n n s ri;i rTi n tpti kis ( Trn <alr ^ 


2 


P-R 


Fusinus ru"osus (Trask) 


4 


P-R 


Haliotis, sp 


4 




Lacuna compaeta Carpenter 


3 


Pl-R 


Lacuna porrecta Carpenter 


3 


Pl-R 


Lacuna solidula Carpenter 


3 


Pl-R 


Leptothyra carpenteri Pilsbry 


3 


Pl-R 


Leptothyra paucicostata Dall 


3 


Pl-R 


Mangilia angulata Carpenter 


q 


P-R 



44 University of California Publications in Geology 



[Vol. 10 



Gastropoda — (Continued) „ Geoi. 

v ' Frequency Range 

Mangilia (Clathurella) conradiana (Gabb) 1 P-E 

Mangilia hexagona Gabb 4 Pl-R 

Mangilia muricidea, n. sp 4 P 

Mangilia oldroydi Arnold 4 PI 

Mitra maura Swainson 4 P-R 

Murex interfossa (Carpenter) 2 P-R 

Murex lurida (Middendorf ) 2 Pl-R 

Murex peritus (Hinds) 2 Pl-R 

Murex, sp 3 

Nassa cooperi Forbes 3 P-R 

Nassa insculpta Carpenter 2 Pl-R 

Nassa mendica Gould 1 P-R 

Nassa perpinguis Hinds 1 M-R 

Natica (Cryptonatica) clausa Broderip and Sowerby 2 Pl-R 

Natica (Euspira) orbicularis Nomland 2 P 

Natica (Neverita) recluziana Petit 2 M-R 

Odostomia, sp. A 4 R 

Odostomia, sp. B 

Odostomia gravida Gould 4 Pl-R 

Odostomia satura Carpenter 4 R 

Olivella intorta Carpenter 3 P-R 

Purpura foliata Martyn 4 Pl-R 

Priehe oregonensis (Redfield) 3 P-R 

Rissoa acutilirata Carpenter 1 P-R 

Seila assimilata (C. B. Adams) 3 Pl-R 

Serpulorbis squamigerous (Carpenter) 2 Pl-R 

Siphonalia gilberti, n.sp 4 P 

Siphonaria, sp 4 

Tornatina cerealis Gould 3 Pl-R 

Tornatina culcitella Gould 3 Pl-R 

Triphoris adversa Montagu 3 Pl-R 

Tritonofusus, sp 

Trophon (Boreotrophon) raymondi Dall, n.sp 2 P 

Trophon (Boreotrophon) gracilis Perry 4 P-R 

Trophon (Boreotrophon) stuarti, var. praecursor Arnold 3 P-Pl 

Turbonilla, sp. A 4 Pl-R 

Turbonilla, sp. B 

Turbonilla tridentata (Carpenter) 4 Pl-R 

Turris (Drillia) modestus, n.sp 4 P 

Turris (Drillia) mercedensis (B. Martin) 3 P 

Turris perversa (Gabb) 1 P-R 

Turris (Drillia) renaudi (Arnold) 3 P-Pl 

Turris (Bathytoma) tryoniana (Gabb) 4 P-R 

Turris (Drilla) inermis(?) (Hinds) 4 P-R 

Turritella cooperi Carpenter 1 P-R 

Turritella jewetti Carpenter 1 P-Pl 

Volutharpa, sp 4 

SCAPHOPODA 

Cadulus nitentor Carpenter 1 Pl-R 

Dentalium hexagonum Dall 3 P-R 



1916] Moody: Fauna of the Fernando of Los Angeles 



45 



PELECYPODA Frequency Range 

Anomia lampe Gray 4 Pl-R 

Area, sp 4 

Cardium corbis Martyn 3 P-R 

Chama exogyra Conrad 2 Pl-R 

Chione simillima (Sowerby) 4 Pl-R 

Chione, sp 4 

Corbula tenuis, n.sp 4 P 

Glycimeris, cf. septentrionalis Middendorf 4 P-R 

Leda haniata Carpenter 1 P-R 

Leda tephria Dall 1 P-R 

Lyonsia californica Conrad 3 P-R 

Macoma ealearea Gmelin 2 P-R 

Maerocallista densa, n.sp 3 P 

Marcia subdiaphana (Carpenter) 4 P-R 

Modiolus, sp 4 

Monia macroschisma (Deshayes) 3 M-R 

Mytilus edulis Linne 4 M-R 

Panope generosa (Gould) 4 P-R 

Panomya ampla Dall 4 P-R 

Pecten (Propeamusium) levis, n.sp 4 P 

Pecten (Pecten) hemphilli Dall 4 P 

Pecten (Patinopecten) caurinus Gould 3 P-R 

Pecten (Hinnites) giganteus (Gray) 3 P-R 

Pecten (Chlamys) hastatus Sowerby 2 P-R 

Pecten (Patinopecten) healeyi Arnold 3 P 

Pecten (Chlamys) hericeus Gould 2 P-R 

Pecten (Chlamys) opuntia Dall 3 P 

Pecten, sp 4 

Petricola carditoides Conrad 3 Pl-R 

Petrieola lamellifera (Conrad) 3 Pl-R 

Phacoides calif ornicus (Conrad) 3 P-R 

Phacoides, cf. annulatus (Reeve) 4 P-R 

Phacoides tenuisculpta (Carpenter) 1 P-R 

Pholadidea penita Conrad 4 P-R 

Protocardia centifllosa Carpenter 4 P-R 

Psephis tantilla Gould 1 Pl-R 

Saxidomus nuttalli Conrad 4 P-R 

Siliqua lucida Conrad 4 Pl-R 

Solen sicarius Gould 2 M-R 

Spisula catilliformis (Conrad) 4 P-R 

Tellina, sp _ 3 

Thracia trapezoides Conrad 4 M-P 

Thyasira gouldi Phillippi 4 Pl-R 

Tivela stultorum Mawe 4 Pl-R 

Venericardia barbarensis Stearns 1 P-R 

Venericardia borealis Gould 1 P-R 

Yoldia scissurata Dall 4 P-R 

Echinoidea 

Strongylocentrotus franciscanus A. Agassiz 1 Pl-R 

Strongylocentrotus purpuratus Stimpson 1 Pl-R 



46 



University of California Publications in Geology [Vol. 10 



CRUSTACEA Frequency Range 

Cancer, sp 1 

Vertebrata 

Indeterminable tooth 4 

Note: Several new species of the Pyramidellidae, found in the fauna, are 
being described by Dr. Bartsch. 



Faunal Summary 

Total number of species 157 

Total number of molluscan species 147 

Gastropoda 97 

Pelecypoda 47 

Scaphopoda 2 

Amphineura 1 

Total number of molluscan species named 131 

Number of extinct molluscan species 22 

Percentage of extinct molluscan species 16.7 

Number of molluscan species confined to northern waters 19 

Percentage of living fauna confined to northern waters 16.4 



General Features op the Fauna 

Aside from the new species described, some uncommon forms have 
been identified from the new locality. A single individual coral was 
found embedded in clay well within a large Natica shell. The species 
has been described by J. O. Nomland 10 as Astrangia insignifica. The 
genus Haliotis is represented by two indeterminate individuals. H. 
lomaensis has been described by Anderson 11 from the Cretaceous of 
Point Loma, but the abalone does not again appear until Pliocene 
time. 12 Good specimens have also been obtained recently from the 
San Diego Pliocene. 

One of the striking features of the fauna is the unusually large 
number of species of Crepidula. Of these C. rugosa and C. princeps 
are represented by a great number of individuals. The latter species, 
remarkable for its large size, is extremely abundant, but singularly 
enough, save for one specimen labeled "Signal Hill," in the collection 
of Stanford University, is unknown from the San Pedro formations, 
although it is listed from this vicinity by Blake in the Geodetic Survey 
Report for 1855. 

10 Nomland, J. O., Univ. Calif. Publ., Bull. Dept. Geol., vol. 9, no. 5, p. 65, 
1916. 

11 Anderson, F. M., Proc. Calif. Acad. Sci., 3d Series, vol. 2, no. 1, p. 75, 
1902. 

isArnold, E,, Mem. Calif. Acad. Sci., vol. 3, pp. 33-34, 1903. 



1916] Moody: Fauna of the Fernando of Los Angeles 47 



Epitonium retiporosa Carpenter for the first time takes its place 
in a fossil faunal list. Murex (Ocinebra) peritus Hinds, Cancellaria 
crawfordiana Dall and Admete gracilior Carpenter, uncommon as 
fossils, appear in splendidly preserved individuals. No less than 
fifteen members of the Turritidae are present, of which Turris perversa 
Gabb occurs in the greatest abundance. Other gastropods which are 
exceedingly abundant are Turrit ella cooperi Carpenter, T. jeivetti 
Carpenter, Columbella carinata Hinds, and Psephis tantilla Could. 

Several species are of interest in their bearing on the correlation 
of the clay deposits with known horizons in the standard Coast Range 
section. Of these the peetens are of great importance ; nine species 
appear in the fauna, eight of which have been identified. Three of 
the recognized species — Pecten healeyi Arnold, Pecten hemphilli Dall, 
and Pecten opuntia Dall — are believed to be confined to the Pliocene. 
An additional form not known to occur above the Pliocene is Thracia 
trapezoides Conrad. Of especial correlative value is the discovery 
in the Los Angeles material of Turris (Drillia) mercedensis Martin 13 
and of Natica orbicularis Nomland, 14 two recently described Pliocene 
species, the former from the Merced of northern California, and the 
latter from the Etchegoin of the southern San Joaquin Valley. 

An anomalous feature of a fauna bearing several restricted Pliocene 
forms is the appearance of Strongylocentrotus in some abundance; 
spines and fragments of the test of both the West Coast species of 
this living echinoid are quite common. Strongylocentrotus has been 
reported from the San Diego beds by Arnold 13 and spines referable 
to this genus, associated with Pecten healeyi and Epitonium varico- 
stata, occur in material collected there by Dr. E. L. Packard. Thus 
the close similarity between the Pliocene fauna of San Diego and the 
Los Angeles fauna is emphasized. 

After a study of the bathymetric range of each species it appears 
that the fauna lived in comparatively shallow water. Of the 114 
living species, nineteen are now confined to waters considerably north 
of the latitude of Los Angeles, although some of them have been 
dredged from deep water south of the Channel Islands. None of 
the species, with the possible exception of a small indeterminable Area, 
can be regarded as typically southern forms. Thus the present geo- 

is Martin, B., Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, no. 7, p. 194, 
1915. 

1* Nomland, J. O., Univ. Calif. Publ., Bull. Dept. Geol., vol. 9, no. 14, p. 65, 
1916. 

is Arnold, R., U. S. Geol. Surv. Prof. Paper, no. 47, p. 28, 1906. 



48 



University of California Publications in Geology [Vol. 10 



graphic range of the Recent species gives the fauna a boreal aspect. 
This evidence may he taken to support the view that the climatic 
environment of the Los Angeles fauna was quite similar to that of 
the San Pedro Pliocene fauna, the boreal character of which is equally 
pronounced, and in which a near-shore character is indicated by the 
lithology of the enclosing beds. 

Comparison with Related Faunas 
It is obvious that the Los Angeles fauna must be referred either to 
the lower Pleistocene or to the upper Pliocene. Before a more definite 
correlation can be made it is necessary to compare percentages and 
individual species with related faunas of recognized stratigraphic 
position. Faunas with which relationships might be anticipated are 
those derived from the Etehegoin, Merced, upper, middle and lower 
Fernando, San Diego and San Pedro formations. 

Revised faunal lists 10 from various horizons in the Etehegoin 
formation of the Southern San Joaquin area show that only eighteen 
species of that formation are found in the Los Angeles fauna, and 
these are for the most part such long-range forms as Natica recluziana 
and Panope generosa. Three supposedly restricted Pliocene species, 
Natica orbicularis, Turris mercedensis and Pecten healeyi, which are 
found at the Los Angeles locality, occur in higher horizons of the 
Etehegoin, and may indicate contemporaneity of later phases of that 
period of deposition with the Los Angeles clays. In the main, however, 
the Etehegoin fauna is decidedly earlier than that of the latter forma- 
tion. Recent work has shown that the percentage of extinct species 
in the fauna of the upper Etehegoin is between 58 and 60, while this 
figure for the Los Angeles beds is 16.7. 

Several points of resemblance appear between the Los Angeles 
fauna and the faunas of the Merced and Purisima formations of middle 
and northern California. The latter faunas, which for the purposes 
of this paper may be considered collectively, are typically boreal. 
Northern types of pectens and mactras abound ; Natica clausa and 
Macoma calcarea occur in many horizons, but the feature which stamps 
the central California Pliocene fauna as incontestably boreal, is the 
great abundance, both specifically and individually, of the Buccinidae. 
This family is much less prominently developed in the southern fauna, 
but is still sufficiently well represented to show an important similarity 
between the two faunas. The upper Merced of the type locality of 



16 Nomland, J. O., Mss. in press. 



1916] Moody: Fauna of the Fernando of Los Angeles 



4!) 



Seven-Mile Beach is now generally conceded to belong to the Pleisto- 
cene ; Martin 17 lists twenty-three species from this horizon, all of which 
are living. From the lower Merced 106 species have been obtained, of 
which fifty-seven, or 53.7 per cent, are extinct. The restricted Pliocene 
forms common to the two faunas are T arris mercedensis, Thracia 
trapezoides, and Pecten healeyi, which has so far been reported only 
from the Purisima. It thus appears that the main body of the Merced 
antedates the Los Angeles deposit, and that the latter formation is 
the time equivalent of only the later horizons of the central California 
Pliocene. 

The Fernando formation, which includes most of the marine Plio- 
cene deposits of southern California, is, in the Santa Clara Valley, 
divided by Eldridge and Arnold 18 into three faunal horizons. The 
lowest horizon is considered as approximately equivalent to the 
Etchegoin, the middle is probably the correlative of the Purisima and 
the lower part of the San Diego formation, while the upper is well 
within the Pleistocene, the higher horizons being correlated with the 
upper San Pedro. The fauna of the lower Fernando, as listed by 
Arnold, contains twenty-nine determined species, of which 55 per 
cent are extinct ; thirty-one species are reported from the middle 
division, with 45 per cent extinct ; from the upper division fifty-one 
species are named, only 12 per cent of which are extinct. From a 
consideration of percentages alone the Los Angeles fauna would 
unhesitatingly be placed near the fauna of the upper Fernando; but, 
as the Los Angeles fauna is nearly three times the size of the latter, 
perhaps a more significant feature is the number of restricted Pliocene 
species which appear from the two formations. In the lower Fernando 
thirteen restricted species are reported, none of wdiieh are found in 
the Los Angeles material. The middle Fernando contains twelve Plio- 
cene forms, with Pecten healeyi alone common to two faunas. No 
characteristic Pliocene forms occur in the upper division. The major- 
ity of the species here classed as "restricted" in the middle and lower 
Fernando are new ; the only Pliocene form that enjoys even a moderate 
geographic range is the above-mentioned pecten. On this basis, includ- 
ing the Astrangia described by Nomland and the ten species described 
in this paper, seventeen restricted Pliocene forms occur in the new 
fauna ; its affinities are thus with the middle and lower divisions of the 

i- Martin, B., Univ. Calif. Publ., Bull. Dept. Geol., vol. 9, no. 15, 191(3. 

is Eldridge, G. H., and Arnold, B., U. S. Geol. Surv. Bull. no. 309, pp. 23-28, 
1907. 



50 



University of California Publications in Geology [ VoL - 10 



Fernando. However, the recent work of English 19 shows that the 
lower Fernando represents a horizon well down in the Pliocene; the 
Los Angeles fauna is therefore probably to be regarded as the time- 
equivalent of only the later phases of the middle Fernando. 

The fauna of the San Diego formation, which has been so thor- 
oughly studied by Dall 20 at the type locality, and by Arnold 21 at 
San Pedro, is in many respects more like that from Los Angeles than 
any of those previously mentioned. Reference has already been made 
to the boreal character of the two faunas. The San Diego formation 
at San Pedro has yielded Arnold eighty- four molluscan species, eighty- 
three of which are determined specifically. Through a typographical 
error Fusinus (Fusus) barbarensis and Mangilia (Clatlmrella) con- 
radiana are listed in his report" as extinct ; with this correction 
(which is made in the faunal list in Professional Paper No. 47, of 
the U. S. Geological Survey) twelve species ( 14.-4 per cent) are extinct. 
Thracia trapezoides is the only one of the three restricted Pliocene 
forms of this locality which occurs in the Los Angeles fauna ; at 
San Diego Pecten opuntia and P. healeyi occur in addition to 
this species. The San Diego formation at the type locality is believed 
by Arnold to include the San Pedro horizon but to extend somewhat 
lower in the Pliocene. 23 The pectens seem to indicate that the Los 
Angeles fauna, while probably the correlative of the lower San Diego, 
is somewhat older than the San Pedro Pliocene. The slightly greater 
percentage of extinct species and the occurrence of Natica orbicularis 
and Turris mercedensis in the former may indicate that the Los 
Angeles horizon belongs even somewhat below the typical San Diego. 

It is the belief of the writer that the fauna obtained from the Los 
Angeles clays represents the later phases of the middle Fernando. It 
is probably somewhat older than the San Pedro deposit, but is the 
equivalent in time of the lower horizons of the San Diego formation. 



is English, W. A., Univ. Calif. Publ., Bull. Dept. Qeol., vol. 8, no. 8, 1914. 

20 Dall, W. H., Proc U. S. Nat. Mus., vol. I, 1878, pp. 10-16, pp. 26-30; 
Proc. Calif. Acad. Sci., vol. 5, 1873, pp. 296-299. 

21 Arnold, B,, Mem. Calif. Acad. Sci., vol. 3, 1903; IT. S. Geol. Surv. Prof. 
Paper, no. 47, 1907. 

22 Arnold, K,, Mem. Cal. Acad. Sci., vol. 3, p. 15, 1903. 

23 Arnold, E., Mem. Cal. Acad. Sci., vol. 3, p. 13, 1903 (correlation table); 
IT. S. Geol. Surv. Prof. Paper, no. 47, 1907. 



1916] Moody: Fauna of the Fernando of Los Angeles 



51 



Description op Species 

EPITONIUM (OPALIA) RETIPOROSA Carpenter 

Plate 1, Figure 3 
Opalia retiporosa Opr., Brit. Assn. Eept., p. 146, 1863 

Shell small, elongate, thick ; spire greatly elevated. Including the 
nucleus there are ten rounded whorls ornamented with fourteen 
irregular, rounded varices. Numerous fine, equally developed spiral 
and transverse ribs intersect at right angles forming a pronounced 
though minutely reticulated structure over the entire surface ; deep 
holes occur between the two systems of sculpture ; the transverse ribs 
pass obliquely over the varices. Suture depressed, distinct. Aperture 
oval ; the nacreous layer is slightly reflexed over the large mouth-varix. 

Dimensions : longitude, 9.2 mm. ; latitude, 3.4 mm. 

So far as known this is the first time that this species has been 
reported as a fossil. The original description of the shell is very 
brief, and, as the single individual found in this deposit is a perfect 
specimen, it has been thought well to redescribe and figure it. 

SIPHONALIA GILBERTI, n.sp. 
Plate 1, Figures 5a, 5b 
Univ. Calif. Coll. Invert. Palaeont., no. 11077. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell fusiform with highly elevated spire. The four or five spiral 
whorls are ventricose, and distinctly angulated above the middle, with 
the angle bearing nine or ten rounded nodes which are faint on the 
body-whorl but strongly and sharply marked on the succeeding whorls ; 
these nodes die out rapidly above and below the angle ; below the 
angulation on the spiral whorls the walls are vertical ; region between 
the angle and the upper suture excavated, producing a collar-like 
effect. Three systems of spiral sculpture ornament each of the whorls ; 
one unit of sculpture consists of two subquadrate ribs about 1.2 mm. 
wide and separated by an interspace 3.9 mm. wide ; medially between 
these ribs is a much less prominent rib about 0.8 mm. wide, and 
flanking it are two yet smaller ones separated from it by deep, 
rectangular grooves and from the main rib by less pronounced grooves. 
On the body-whorl there are seven units of the major sculpture below 
and one on the angle, while six ribs of equal strength mark the 
excavated region between the angle and the suture. Primary and 



52 



University of California Publications in Geology [Vol. 10 



medial ribs reflected interiorly on the outer lip by ridges and grooves. 
Shell longitudinally sculptured only by numerous fine incremental 
lines. Aperture oval, although somewhat constricted toward the canal- 
end ; sutural notch deep ; outer lip thin ; inner lip smooth, and fairly 
heavily incrusted. Umbilicus excavated, but imperforate ; columella 
light and straight ; canal short and pronouncedly recurved. 

Dimensions. — Longitude, 78 mm. ; latitude, 47.3 mm. 

This species agrees in its broad features with Thais kettlemanensis 
Arnold described from the Jacalitos, but is readily distinguished by 
the greater height of spire, more acute apical angle, greater inclination 
of the spiral sculpture to the columellar axis, deeper sutural notch, 
sharper recurving of the canal and by the pronounced rounding groove 
above the sharp angle. It is quite distinct in outline and sculpture 
from the recent Siphonalia kelletti, but its aperture and canal char- 
acters place it in the same genus. 

Two reasonably well preserved specimens were found. 

CIIEYSODOMUS DIRUS MERIDIEI, var. nov. 
Plate 1, Figures 9a, 9b 
Univ. Calif. Coll. Invert. Palaeont., no. 11078. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell medium-sized, short, fusiform. The elevated spire is made 
up of six or seven rounded whorls ornamented with about ten trans- 
verse rounding nodes which die out toward the sutures and are nearly 
obsolete on the body-whorl. The body-whorl possesses a tendency 
toward tabulation due to a faint angulation in the middle portion 
of its upper half. The shell is ornamented by seventeen strong, 
squarish, equally spaced ribs, the interspaces being three-fourths the 
width of the rib. The suture is strongly appressed and, due to the 
enlargement of the last spiral rib and to the excavated subsutural area, 
appears to bear a collar. Aperture subquadrate ; inner lip incrusted; 
outer lip heavily thickened ; umbilicus imperforate ; canal short and 
strongly recurved. 

Dimensions. — Longitude, 44.1 mm.; latitude, 21.6 mm. 

Comparison with C. dims shows that, while probably belonging 
to the same species, this form possesses characters sufficiently marked 
to give distinction to the variety. Among the more important differ- 
ences are the presence of the angulation, the sharply curved canal, and 
the heavy thickening of the outer lip of the Los Angeles form. The 



1916] Moody: Fauna of the Fernando of Los Angeles 53 



ribbing is found to be heavier on the variety ; and further only seven- 
teen spiral ribs occur on it, while from twenty to twenty-two appear 
on each of the specimens of C. dims in the University of California 
museum collection. 

Only one individual was found. 

TEOPHON EAYMONDI, n.sp. 
Plate 1, Figures la, lb 
Univ. Calif. Coll. Invert, Palaeont., no. 11088. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell small, enlongate, fusiform ; spire consists of four tabulated 
whorls with cylindrical walls, each bearing about twelve pointed 
spinous nodes which project above the prominent angulation, but die 
out rapidly below in the faint transverse ridges which alone ornament 
the whorls. Body-whorl ventricose, enlongate, bearing fourteen sharp 
nodes which increase in size and elevation above the tabulation toward 
the peristome ; no spiral sculpture ; transverse ornamentation consists 
merely of coarse incremental lines. Aperture enlongate ; outer lip 
thick, slightly reflexed ; inner lip smooth, not incrusted ; columella long, 
straight; canal long, straight, narrow. 

Dimensions. — Longitude, 14.0 mm. ; latitude, 5.0 mm. 

The long straight canal, sharp nodes, and unadorned whorls of this 
form seem unique characters which readily permit its separation from 
other members of this genus on the coast. 

At least eighteen well preserved specimens were obtained which 
show great variation in size, the dimensions given being those of an 
average specimen. 

COLUMBELLA (ASTYBIS) CONSTANTIA, n.sp. 
Plate 1, Figures 7a, 7b 
Univ. Calif. Coll. Invert. Palaeont., no. 11079. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell small, light, rather thick; apex acute, with seven slightly 
rounded whorls. The body-whorl bears an indistinct angulation below 
the center, but except for very fine incremental lines the whorls are 
otherwise unadorned. The suture is distinctly appressed. The 
columella is recurved and striated inside and outside with from nine to 
twelve spiral ridges which rapidly die out as the body-whorl enlarges 
from the pillar. Aperture elliptical ; inner lip smooth and not in- 
crusted; outer lip thin, without crenulations. The canal is long, 
narrow and recurved. 



54 University of California Publications in Geology [Vol. 10 



Dimensions. — Longitude, 8 mm. ; latitude, 3.6 mm. 

The number of whorls and the enlongate, narrow canal serve to 
distinguish this species from its nearest relative, C. gausapata, which 
also occurs in some abundance in the material. Crenulations on the 
outer lip are absent in all the specimens, hence some doubt is enter- 
tained in placing the form in the subgenus Astyris. 

A dozen or more individuals were found, several of which are 
perfectly preserved. Many of the shells show a fine polish. 

TUREIS (DRILLA) MODESTUS, n.sp., 
Plate 1, Figure 8 

Univ. Calif. Coll. Invert. Palaeont., no. 11080. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell very small, conical, turreted, with elevated spire ; lateral out- 
line very slightly concave. There are seven conical whorls, each 
bearing near the base a faint double angulation determined by two 
heavy spiral ribs which appear nodose from the intersection of an 
equally developed set of transverse ribs. The body-whorl is orna- 
mented with twelve distinct but not prominent spiral ribs below the 
lower angulation and extending well out on the canal ; two ribs of 
intermediate prominence appear above the upper angulation ; the 
transverse sculpture consists of sixteen equidistant, equally developed, 
slightly obliquely directed longitudinal ribs, which are obsolete on 
the last three spiral whorls. The suture is rather conspicuously 
depressed. Aperture elliptical ; outer lip unknown ; inner lip incrusted, 
smooth. The canal is of moderate length, narrow and slightly 
recurved. 

Dimensions. — Longitude. 5.2 mm.; latitude, 1.9 mm.; apical angle, 
20 degrees. 

The size, shape and ornamentation of this species serve to separate 
it from other known members of the Turritidae. 

One specimen only was found, from which the peristome had un- 
fortunately been broken. 

BORSONIA INCULTA, n.sp. 
Plate 1, Figures 2a, 2b 
Univ. Calif. Coll. Invert. Palaeont., no. 11081. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell small, turreted, broadly fusiform, with a moderately elevated 
spire. Six whorls appear, each bearing a double angulation of which 



1916] Moody: Fauna of the Fernando of Los Angeles 



55 



the superior one is the more strongly marked. Suture well defined by 
a strongly depressed line which is partially covered by a somewhat 
obscure collar projecting from the whorl below. The interangulation 
portions of the whorls have parallel walls, and this feature, together 
with the low pitch of the spire, gives a subquadrate appearance to each 
whorl. Ornamentation of the body-whorl consists of two very faint 
revolving ribs above the upper angulation, and three somewhat more 
pronounced ones below the lower angulation ; transverse sculpture 
limited to very numerous, fine incremental lines, which are convexly 
reflexed posteriorly at the upper angulation, forming a broad tur- 
ritoid embayment at this point. Aperture elongated and somewhat 
rectangular, with prominent sutural notch at top. Outer lip thin ; 
inner lip smooth, and lightly incrusted. The canal is deep, short 
and recurved. 

Dimensions. — Longitude, 13.5 mm. ; latitude, 6.9 mm. 

The short canal and low pitch of the spire serve to distinguish this 
form from related species. The type specimen presents a very rough, 
uncouth appearance due in part to erosion, in part to unequal develop- 
ment of the lines of growth, but largely to attack from parasitic or 
marauding neighbors. 

One specimen was found in the material available. 

MANGILIA MURICIDEA, n.sp. 
Plate 1, Figures 10a, 10b 
Univ. Calif. Coll. Invert. Palaeont., no. 11082. Type locality, Fourth ami 
Broadway, Los Angeles. 

Shell very small, elongate, fusiform, with an elevated spire. The 
six convex whorls are ornamented with very coarse, reticulating ribs ; 
each whorl bears two very strongly marked spiral ribs which produce 
a faint double angulation; two ribs of lesser weight appear above 
the central ribs and four below; the interspaces between both major 
and minor ribs contain small inter-ribs on the body-whorl. The longi- 
tudinal sculpture consists of fourteen prominent, slightly obliquely 
directed ribs with quite narrow interspaces. The intersection of the 
two systems of ornamentation produces a nodose effect. The suture 
is strongly depressed. The ovate aperture bears an obscure sutural 
notch; outer lip unknown, inner lip smooth. The canal is long, 
broadly tapering, and nearly or quite straight. 

Dimensions. — Longitude. 7 mm. ; latitude, 2.9 mm. 



56 



University of California Publications in Geology [Vol. 10 



The coarse sculpture of this species, which resembles that of many 
of the Muricidae, is believed to differentiate it from other members 
of the genus. 

One specimen only was found, from which the outer lip had been 
broken. 

CANCELLAEIA QUADEATA, n.sp. 
Plate 1, Figure 6 

Univ. Calif. Coll. Invert. Palaeont., no. 11083. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell small, low, fusiform, with a moderately elevated spire, which 
is perhaps one-fourth the length of the shell. There are six angulated, 
strongly tabulated whorls, with parallel walls. Sculpture of the body- 
whorl consists of four equally developed, equidistant spiral ribs below 
the tabulation, with smaller, low, rounding ribs in the interspaces, 
and four indistinct ones on the tabulation ; ten prominent longitudinal 
ridges intersect the spiral sculpture at right angles and exhibit a 
tendency toward the development of spinous nodes on the angulation. 
Aperture oval, constricted anteriorly ; outer lip is unknown ; inner lip 
bears eight spiral lines concentric with the two sharp columellar 
plications. The pillar is strongly curved away from the aperture ; 
canal broad and probably short. 

Dimensions. — Longitude unknown ; latitude, 7.5 mm. 

The tabulation of the whorls, character of the sculpture and sharp- 
ness of the columellar plaits are unique features of this form. 

One specimen only was found ; a large part of the body-whorl and 
the canal are lacking. 

PECTEN (PEOPEAMUSIUM) LEVIS, n.sp. 
Plate 2, Figures 2a, 2b, 2c, 2d 
Univ. Calif. Coll. Invert. Palaeont., no. 11084. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell small, thin, translucent, nearly circular in outline, equilateral, 
compressed, slightly inequivalve. Right valve is smooth except for 
numerous very fine incremental lines, which occasionally are enlarged 
and roughened; traces of submiscroscopic radiating striae are to be 
seen. Hinge line is about five-eighths the width of the shell; ears 
sharply set off from the disc by equal impressed lines which are nearly 
straight and slope evenly from the umbone ; anterior ear arcuate, 
coarsely sculptured by about fourteen subequal ridges which radiate 



1916] Moody: Fauna of the Fernando of Los Angeles 



57 



from the beak, and by about thirty-five prominent, regular, imbricating 
lines of growth which curve outward, following the anterior margin ; 
posterior margin makes a right angle with the hinge-line ; byssal notch 
almost obsolete ; posterior ear ornamented with a similar number of 
incremental laminae which are only slightly curved and are nearly 
vertical, the radiating ridges being indistinct. Interior surface of the 
valve marked by twenty-two rounding ridges which radiate from the 
apex but are partially obscured in the upper portions by a callus 
growth which covers one-third the area of the disc ; a single adductor 
scar appears on the anterior dorsal margin of the callus. Left valve 
slightly less convex than the right ; externally sculptured by fourteen 
prominent, smooth, rounded ribs which radiate from the apex; in the 
interspace appear one or sometimes two inter-ribs of varying length, 
which never reach the beak ; anterior ribs and inter-ribs slightly imbri- 
cated ; incremental lines quite fine and uniform on the posterior three- 
fourths of the surface. Ears of the left valve subequal ; both slightly 
arcuate below the hinge line, the anterior more coarsely sculptured 
by twelve radiating striae and thirty or more roughened incremental 
lines which are vertical on the hinge-line and broadly recurved below ; 
beak sharp and straight and slightly raised above the hinge-line. 
Interiorly the valve is sculptured by about twenty distinct, rounded 
ribs radiating from the umbone, which are independent of the external 
ornamentation and do not reach the ventral margin ; internal ribs 
slightly obscured, as in the right valve, by a callus growth. 

Dimensions. — Latitude, 16 mm. ; longitudinal diameter, 15.6 mm. 

This little pecten is one of four members of the subgenus 
Propeamusium known from the West Coast. P. davidsoni and P. 
alaskensis are living forms now inhabiting deep waters from Van- 
couver Island to Bering Sea ; the latter species is said to occur 
as far south as Panama Bay, and is known from Pleistocene deposits 
on Vancouver Island and in southern Alaska. Pecten riversi Arnold 
is a closely related form from the Santa Monica Canon Pliocene. 
Prom the descrijdion of P. riversi it appears that one of the chief 
characters of the species is the retarded development of the internal 
lirae, which do not appear until the shell has attained an altitude of 
15 mm. In P. levis these internal riblets persist to the apex, a char- 
acter of P. alaskensis. Other characters which serve to distinguish 
this species from P. riversi are the smooth incremental lines on the 
otherwise unadorned surface of the right valve, the lack of imbri- 
cation on the ribs of the left valve, and in this valve, the failure of 



58 



University of California Publications in Geology [Vol. 10 



the internal riblets to reach the periphery. The external sculpture 
of the left valve and the outline and submicroscopic radiating striae 
of the right, described in the new species, are characters quite distinct 
from P. alaskensis. 

Four specimens were found, of which two are nearly perfect 
left valves, and of the two right valves, one is nearly intact. 

MACROCALLISTA DENSA, n.sp. 

Plate 2, Figures la, 1ft 

Univ. Calif. Coll. Invert. Palaeont., no. 11086. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell small, thick, broadly subovate, inequilateral, moderately con- 
vex. The prosogyrous beaks are moderately elevated. Surfaces of 
both valves marked by fine incremental lines which occasionally are 
somewhat enlarged and roughened. Anterior and posterior ends evenly 
rounded, but as the posterior is somewhat the broader, the shell appears 
subtruncate. Posterior dorsal margin straight fom the umbo to one- 
half the distance to the posterior end; ventral margin smooth and 
thick. No escutcheon appears, and the lunule is very faintly marked 
by a circumscribing line. Three prominent cardinal teeth appear 
in each valve, the posterior being longer and narrower than the other 
two and strongly bifid in each valve. In the right valve are two 
prominent anterior elaspers while a corresponding lateral appears in 
the left; the ventral lateral in the right valve is in alignment with 
the anterior cardinal, which is shortened. The nymph plate is smooth 
and, in the right valve, is elevated at some distance posterior to the 
last cardinal. The external ligamental groove is long and relatively 
broad. In the right valve the hinge plate bears a rounding embay- 
ment ; in the left it is triangular. Pedal scars indistinct ; pallial line 
distant from the ventral margin ; pallial sinus capacious and broadly 
rounding. 

Dimensions. — Altitude, 7.4 mm. ; diameter, 8 mm. 

This beautiful little shell possesses unique characters in the placing 
of the anterior laterals and in having both posterior cardinals bifid. 
No near relatives of the form appear in the California Tertiary. 

Four specimens were found, of which one is a right valve slightly 
broken. 



1916] Moody: Fauna of the Fernando of Los Angeles 59 



CORBULA TENUIS, n.sp. 

Plate 2, Figures 4a, 46 

Univ. Calif. Coll. Invert. Palaeont., no. 11087. Type locality, Fourth and 
Broadway, Los Angeles. 

Shell small, triangular, very thin, with prominent subcentral 
prosogyrous beaks which are strongly incurved. Anterior end 
elongated and evenly rounded ; posterior end rounded, but the 
posterior portion of the shell possesses a posteriorly directed keel 
passing from the umbo obliquely to the ventral margin which 
sets off the posterior one-fourth of the shell from the remainder, and 
makes a small angle within the posterior margin. A few indistinct 
lines, radiating from the beak, are seen on this posterior one-fourth 
of the shell ; the remaining portion is smooth, except for very fine 
incremental lines. In the right valve appears one prominent cardinal 
tooth anterior to the small cartilage-pit ; the anterior dorsal margin is 
produced into a sharp lamellar plate. The anterior adductor scar is 
elongate, but the posterior is unknown ; pedal scar distinct, situated 
above the adductor. The left valve is unknown. 

Dimensions. — Altitude, 7.8 mm. ; diameter, 8.6 mm. 

The extreme delicacy of shell in this species is one of its most 
distinctive features. The outline, while rather imperfectly shown in 
the figures, is also quite distinct from that of any known Corbtila. 

Two rather imperfect right valves were found. 



EXPLANATION OF PLATE 1 



Fig. 


la. 


Fig. 


lb. 


Fig. 


2a. 


Fig. 


2b. 


Fig. 


3. 


Fig. 


4. 


Fig. 


5a. 


Fig. 


5b. 


Fig. 


6. 


Fig. 


7a. 


Fig. 


76. 


Fig. 


8. 


Fig. 


9«. 


Fig. 


96. 


Fig. 


10a, 


Fig. 


106 



Trophon raymondi, n.sp., front view, x 2. 

Trophon raymondi, n.sp., back view, x 2. 

Borsonia inculta, n.sp., front view, x 3. 

Borsonia inculta, n.sp., back view, x 3. 

Epitonium retiporosa (Carpenter). x3. 

Admete graciUor (Carpenter), x 2. 

SipJionalia gilberti, n.sp., front view. Natural size. 

Siphonalia gilberti, n.sp., back view. Natural size. 

Cancellaria quadrata, n.sp.; canal and body-whorl lacking, x 

ColumbeUa constantia, n.sp., back view, x 3. 

Columbella constantia, n.sp., front view, x 3. 

Tun-is modestus, n.sp. x 3. 

Chrysodomus dints meridiei, n.var., back view. Natural size. 
Chrysodomus dirus meridiei, n.var., front view. Natural size. 

Mangilia muricidea, n.sp., back view, x 3. 

Mangilia muricidea, n.sp., front view, x 3. 



[60] 



UNIV, CALIF. PUBL. BULL. DEPT. GEOL. [MOODY] VOL. 10, PL. I 




EXPLANATION OF PLATE 2 

Fig. la. Macrocallista densa, n.sp. Internal view of right valve. X 2. 

Fig. lb. Macrocallista densa, n.sp. External view of right valve, x 2. 

Fig. 2a. Pecten levis, n.sp. External view of right valve, x 2. 

Fig. 2b. Pecten levis, n.sp. Internal view of right valve, x 2. 

Fig. 2c. Pecten levis, n.sp. External view of left valve, x 2. 

Fig. 2d. Pecten levis, n.sp. Internal view of left valve, x 2. 

Fig. 3. Clirysodomus rectirostris (Carpenter), x 1.5. 

Fig. 4a. Corbula tenuis, n.sp. Internal view of right valve, of type spec 
en. x 3. 

Fig. 4J>. Corbula tenuis, n.sp. External view of left valve, cotype. x 3. 

Fig. 5a. Cancellaria crawfordiana Dall, front view, x 2. 

Fig. 5b. Cancellaria crawfordiana Dall, back view, x 2. 

Fig. 6. Natica orbicularis Nomland. Natural size. 

Fig. la. Turris mercedensis (Martin), back view, x 2. 

Fig. 7b. Turris mercedensis (Martin), front view, x 2. 



LG2| 



UNIV. CALIF. PUBL, BULL. DEPT. GEOL 



[MOODY] VOL. 10, PL. 2 




UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. S, pp. 63-73, 5 text-figures Issued November 6, 1916 



NOTES ON THE MARINE TRIASSIC REPTILE 
FAUNA OF SPITZBERGEN 



BY 

CARL WIMAN 



z" 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 5, pp. 63-73, 5 text-figures Issued November 6, 1916 



NOTES ON THE MARINE TRIASSIC REPTILE 
FAUNA OF SPITZ BERGEN 

BY 

GAEL WIMAN 



CONTENTS 

Introduction 

Occurrence 

Mixosaurus and Phalarodon 

Pessosaurus and Shastasaurus 

Pessopteryx and Omphalosaurus 

Faunal Relationships 

Literature 

INTRODUCTION 

It gives me great pleasure to comply with a request from two 
American colleagues to make a comparison between the marine Triassic 
reptiles of Spitzbergen and Europe on the one hand and western North 
America on the other, and I do this so much the more because on both 
sides a good deal has come to light since I treated the Triassic ich- 
thyosaurs from Spitsbergen in 1910.-"* Of reptiles, however, very 
little material has been added from the Trias of Spitzbergen since the 
saurian expedition in 1909. The expeditions of 1912 and 1913 have, 
like the one that is now in progress, been directed chiefly to the some- 
what older fish horizon with stegocephalians and fishes. 

OCCURRENCE 

Not very long ago the iehthyosaurians from the Trias belonged to 
the greatest rarities ; now, on the contrary, they seem to be about 

* For literature references see bibliography forming the last division of this 
paper. 

Owing to uncertainty of transport timing the past year it has not been 
jjossible for the author to read the proof of this paper. — Editor. 



63 
63 
65 
68 
69 
71 
73 




University of California Publications in Geology 



[Vol. 10 



equally rich in species, and at least in the northern hemisphere as 
widely distributed, as during the Jurassic. One knows of finds at a 
number of places in Germany, Switzerland, Italy, Austria, Rouma- 
nian England, Spitsbergen, arctic and western North America, and 
possibly New Zealand. Among these many finds there are, however, 
only a few that have given any, palaeontologically, more enlightening 
material. Tbe richest and most important have been the finds in the 
Daonella limestone, in the West Humboldt Range in Nevada, of Middle 
Triassic age ; and in California, in the Hosselkus limestone, of Keuper 
age. 10 

The occurrence in northern Italy and Switzerland, just southeast 
of the southern extremity of Lake Lugano, generally known under the 
name of Besano, has been productive since the fourth decade of the 
nineteenth century, and was, though hardly yet fully appreciated, for 
a long time the only source of knowledge regarding the structure of 
the Triassic ichthyosaurians. These occurrences belong to a lower 
horizon of Keuper, Raibl-St. Cassian. 1 

The German occurrences have hitherto yielded little, but recently 
a new find has been made, and the material scattered in various mu- 
seums has been brought together, so that von Huene 7 has been able to 
show that twenty species, representing seven genera, are to be found. 
Of these, however, only eight species are sufficiently represented to 
make it possible for them to be named. Of the seven genera six are 
represented in other species from California, Nevada, Spitsbergen, 
and Besano. The whole of the material seems to come from the 
Muschelkalk. 

The Spitzbergen Trias vertebrates are, with a few exceptions, dis- 
tributed in four horizons. If the lowest, the first horizon, is fixed at 
zero, they lie at something like the following distances from each other : 

The new vertebrate horizon 360 ? m. 

The upper saurian horizon 205-210 



With regard to stratigraphy in general, reference is made to the 
work by Nathorst. 16 Above the arenaceous beds, belonging presum- 
ably to the Buntsandstein,-" which were previously referred to the 
Permian, come the Posidonomya slates. Near the base of these lies 
the fish horizon, and somewhat deeper than that part of the layer 
which from older Swedish ammonite finds was known to Mojsisovics. 15 
Probably the lower saurian horizon also comes within this layer. 



The lower saurian horizon 
The fish horizon 



93 




1916] Wiman: Marine Triassic Reptile Fauna of Spitsbergen 



65 



The Posidonomya slates, as well as the following Daonella slates, with 
the upper saurian horizon, belong to the Musehelkalk. Above these 
bituminous slates again come arenaceous beds which, for the greater 
part at least, ought to represent the Keuper. Within these lies the 
new vertebrate horizon. 

The age relations of the better known Triassic ichthyosaurians 
thus becomes the following : To the Middle Triassic belong the finds 
in Germany, Nevada, and Spitzbergen, and to the Upper Triassic those 
in California and at Besano. 

MIXOSAUEUS AND PHALAKODON 

The genus Mixosaurus was erected by G. Bam* 12 in 1887, and was 
founded on the Lombardy species M. cornalianus Bass., which now, by 
the researches of Repossi 18 and myself, 21 is pretty well known. In 
1891 E. Fraas r ' incorporated with this genus, under the name Ich- 
thyosaurus atavus, the species originally described by Quenstedt. 17 
This procedure was accounted for by I. atavus having elongated fore- 
arm bones, sparse and dimorphous teeth, etc., characters which one 
now knows are peculiar to Triassic ichthyosaurians in general, and 
therefore cannot be used as generic characters. For the same reason 
Dames 3 took this view. Judging by the little hitherto known of 
I. atavus, it cannot belong to the genus Mixosaurus. 

For still less important reasons Dames referred to the genus Mixo- 
saurus the smaller of the only two species from the Spitzbergen 
Triassic. This, however, has turned out more successful, and new 
material having been added since 1909, I did not hesitate, in 1910, to 
class Mixosaurus nordenskidldi with this genus. In this view I have 
been further strengthened since I succeeded in obtaining material of 
the Besano species and studied Repossi 's original specimens in Milan. 

In 1910 a work by Merriam 12 was published in which a new species, 
Phalarodon f raasi, was described. It then appeared that I had prob- 
ably made a mistake, in so far as I had also classed the Phalarodon- 
like jaw fragments with Mixosaurus nordenskidldi (1910, pi. 5, figs. 
10, 12, and 13). In so doing I conceived the possibility of a difference 
in sex of such a nature that the less pronounced dimorphous teeth 
might represent, for example, young females and the more developed 
dimorphous teeth old males. My figure 10 shows a transition, on the 
one hand, from those which I still wish to class with Mixosaurus 
nordenskidldi (figs. 9 and 11) and the perfectly Phalarodon-like ones 
in figures 12 and 13. 



(ili 



University of California Publications in Geology [Vol. 10 



In his work of 1911 Merriam 13 called attention to the similarity 
between Phalarodon and certain of my specimens, and I now consider 
it probable that the jaw fragments (pi. 5, figs. 12 and 13) at least, 
are to be connected with Phalarodon, which is a special type. After 
having seen comprehensive material of Mixosaurus cornalianus, I have 
found that the appearance of the teeth is very constant in different 
specimens, and from investigations by Dollo 4 of the mosasaurian 
Globidens fraasi, in which also Phalarodon is treated, it has also be- 
come probable that the posterior teeth of Phalarodon indicate a very 
diverging diet. As, however, there is in the grade of dimorphism of 
the teeth a very even transition from M. cornalianus over M. norden- 
skioldi and to the pronounced Phalarodon type, one ought perhaps to 
await a more complete knowledge of the crania of the Mixosaurus 
species, and new discoveries of remains of PJtalarodon, of which 
hitherto only cranium parts are known, before one decides where the 
boundary between Mixosaurus and Phalarodon should be fixed, and 
whether the difference really is so great that it warrants the setting 
up of a new genus. For the present I will, therefore, keep M. corna- 
lianus and .1/. nordenskioldi together within the same genus. To it 
belongs, with a certain degree of possibility, also Cymbospondylus? 
nutans Merriam from Nevada. The anterior limb indicates, as will 
be seen by the accompanying figures (figs. 1 and 2), great similarity, 
especially to the species from Spitsbergen. The piece of the vertebral 
column, which Merriam classes with this species, does not contradict 
this supposition. It is perhaps not excluded that Phalarodon fraasi 
is the cranium of this species, for it originates from the same horizon. 

The pelvic arch of M. nordenskioldi is, as I have previously shown, 
almost identical with that of M. cornalianus, which has also a foramen 
pubicum. 

As Merriam has rightly observed from my figure of the vertebral 
column, a portion of the tail is missing, but it is seen from loose 
vertebrae that the tail has not narrowed off suddenly, as with the 
w hales, but very slowly, as with other ichthyosaurians. The part of 
the tail that lay behind the caudal fin must therefore have been very 
long. Merriam also conceives of the possibility of my having placed 
the pelvis too far back. This I do not consider probable, for I am 
very sure about the position of the pelvis. The difficulties that Mer- 
riam finds in the, with all this connected, placing of the caudal fin 
disappears if one takes another view of the origin of the caudal fin 
than Merriam. I have imagined that the caudal fin is a dorsal fin, 



1916] Wiman: Marine Triassic Reptile Fauna of Spitzbergen 67 



which moves backwards, and first during the Jura period reaches the 
tip of the tail, where it becomes stationary, after which the portion 
of the vertebral column located within the fin begins to shrink. In 
this view of mine I have also been strengthened by Fraas'" description 
of the remains of a very young specimen of Ichthyosaurus quadri- 
scissus Quenst., which in this respect constitutes something between, 
for instance, Mixosaurus nordcnskioldi and the full-grown /. quadri- 




Fig. 1. — Mixosaurus? natans Mer- Fig. 2. — Mixosaurus nordensJcidldi 

riam. Anterior limb, X % (combined Hulke. Anterior limb, X % (after 

after Merriam and partly restored). Wiman). 

H, humerus ; E , radius ; V, ulna. 

scissus. It then also becomes perfectly natural that the fin-defining 
downward bend of the tail in the older Middle Triassic M. norden- 
sJcidldi, lies more forward than in the younger Upper Triassic M. 
cornalianus, in which the fin ought to have had time to move a little 
farther back. In Cymb ospon dylus petrinus, also Middle Triassic, 
the tail-curve lies, according to Merriam, still farther back than in 
the younger M. cornalianus. This, however, need prove nothing more 
than that in another quite different tribe of ichthyosaurs the move- 



68 



University of California Publications in Geology [Vol. 10 



ment of the caudal fin took place at a quicker pace than in the 
mixosaurians. 

PESSOSAURUS AND SHASTASAURUS 

Of the material from the upper saurian horizon of Spitsbergen, 
which I have tried to unite with Pessosaurus polaris Hulke, only the 
coracoid, humerus, radius, idna and a few podial bones are found to- 




Fig. 3. — Shastasaurus osmonti Mer- Fig. 4. — Pessosaurus polaris Hulke. 

riam. Anterior limb, X % (after Anterior limb, X J /4. 

Merriam). 

C, coracoid ; H, humerus; B, radius; U, ulna; I, intermedium; T, trochanter. 

gether. As the ulna was destroyed in the preparation, I have not 
figured it before, although a very important fragment in juxtaposition 
to the radius is left. The bone had, however, the shape, very nearly 
at least, that I have reproduced in the accompanying figures (figs. 3 
and 4). This neglect on my part has doubtless contributed to the 
peculiarities of the species, over against Shastasaurus, not having ap- 
peared as clearly as could have been desired. A comparison between 



1916] Wiman: Marine Triassic Reptile Fauna of Spitzbergen 69 



the figures of Pessosaurus polaris Hulke and Shastasaurus osmonti 
Merriam proves that quite another type is before us. The coraeoid 
undeniably shows a certain likeness to the same bone in Shastasaurus, 
but it is more elongated longitudinally, which, however, is of little 
importance. This type of humerus differs widely from all the Amer- 
ican species and recurs only in Pessopteryx, the species of which, one 
and all, possess this thick, round type. Also radius and ulna have an 
appearance diverging very much from all other forms, caused by their 
belonging to a species with short, broad fins, within which the dis- 
placement of the bones has proceeded farther than with any other 
Triassic ichthyosaurian. For though the, for all such typical remain- 
ing portion of the forearm, elongation still is marked by the round not 
cartilage-filled hole between the radius and the ulna, the intermedium 
has pressed in just as far between the forearm bones as, for instance, 
in the Jurassic Ichthyosaurus communis Conyb. The fore limb of 
Pessosaurus thus shows arrangement and form of the bones quite 
different from the corresponding characters in Shastasaurus. 



PESSOPTERYX AND OMPHALOSAURUS 

The material from the Lower Saurian horizon of Spitzbergen is 
very difficult to handle, as it consists of mere loose bones and bone 
fragments which lie scattered on the float soil. Most of the bones are 
present in a very great number of specimens, and I still consider it 
probable that the majority belong to an ichthyosaurian which I have 
called Pessopteryx nisseri. In addition, some smaller species chiefly of 
the same time must be present. 

To Pessopteryx nisseri I also referred, by way of proposal, and 
with much hesitation, a large number of jaw fragments with queer, 
button-like teeth in several rows. When I referred these teeth to an 
ichthyosaurian I imagined a change of diet something like the one 
that has now really been verified in Phalarodon and Globidens. That 
the teeth were set in several rows I imagined to be due to the fact that, 
for the greater part at least, they consisted of reserve teeth, not yet 
used, which in that case ought to be arranged much the same as with 
the crocodiles, although, as far as I have yet been able to ascertain, 
they lie wholly embedded in the bone substance. Resorption of bone 
substance is of course nothing unusual in connection with displace- 
ment of teeth and horny cases, and also the embryological origin of 
similar teeth ought to be histologically possible. 



7(1 



University of California Publications in Geology L Vo1 - 10 



These jaw fragments now seem to me to be somewhat less enig- 
matical, since Merriam has pointed out that they do not belong to an 
Ichthyosaurian. In 1906 Merriam 9 described a reptile, widely dif- 
ferent from the ichthyosaurians but with a still uncertain systematic 
position, Omphalosaurus. It is found in the Middle Triassic of 
Nevada, and is thus approximately in the same horizon as Pessopteryx. 
The reproductions of the teeth of Omphalosaurus that are found 
in this work did not suggest to me any thought of the enigmatical 
teeth of Spitzbergen. Merriam, however, in 1911, 13 has shown 
the great similarity between the Omphalosaurus teeth and the teeth 
referred by me to Pessopteryx, and since Merriam and Bryant 14 the 
same year prod viced new figures of Omphalosaurus teeth I can myself 



Fig. 5. — Phalanges from the Lower Saurian horizon on Spitzbergen, X % 
(after Wiman). 

state the identity. But seeing that the teeth are identical, in what 
relation do then Omphalosaurus and Pessopteryx stand to each other? 
Of the former only parts of the cranium with teeth and biconcave, 
iehthyosaur-like cervical vertebrae are known, and, again, of the latter 
vertebrae, extremity and girdle bones are found. Therefore a com- 
parison cannot be made. One can, however, think of two possibilities. 
The one is, that all of the material represents Omphalosaurus. Mer- 
riam seems to be inclined to this interpretation. One would then have 
to imagine a reptile with a relatively short head and a body that in 
detail had developed on the same line as Ichthyosaurus. Such a paral- 
lelism is of course not inconceivable, but less probable. The other 
probability is that an ichthyosaurian Pessopteryx is before us, but 
that, together with its bones, jaw fragments of Omphalosaurus occur. 
It is easily possible that these very jaw bones have constituted the most 
lasting part of the skeleton. In favor of a foreign intermixture also 
speaks the fact that together with the Pessopteryx bones occur very 




1916] Wiman: Marine Triassic Reptile Fauna of Spitzbergen 



71 



numerous phalanx-like bones of different length, which, as I have pre- 
viously pointed out, cannot be located in an ichthyosaurian skeleton, 
but which might possibly belong to the Omphalosaurus teeth. That 
an ichthyosaurian Pessopteryx should develop a peculiarly formed 
humerus, which is identically like that of another ichthyosaurian, 
Pessosaurus, from the same region, is by far not so strange as that a 
reptile of an altogether different tribe, Omphalosaurus, should acquire 
just this humerus type. I therefore consider the probability larger 
that in addition to Pessopteryx nisseri also a representative of the 
genus Omplialosaunis is before us. 

FAUNAL RELATIONSHIPS 

I can therefore agree with Merriam that the marine Triassic 
saurians of Spitzbergen and of central and southern Europe show a 
noticeable similarity with those of the Triassic of North America. 
The Mixosaurus species nordenskioldi, cornaUanus, and nutans are 
undoubtedly nearly related. If, then, a separate genus, Phalaradon, 
be added, common to Spitzbergen and western North America, this 
of course increases the similarity. Judging by von Huene's previous 
communications, a number of American ichthyosaurian genera are also 
to be found in the middle European Muschelkalk. Omphalosaurus, 
wherever it belongs, is also a genus common to Spitzbergen and North 
America. 

If, however, important similarities exist between the Triassic marine 
saurians in the Old and the New World, there are also greater dis- 
similarities. These differences appear among the ichthyosaurians. In 
western North America are found numerous species of the genera 
Cymbospondylus, Toretocnemus, Merriamia, Delphinasaurus, and 
Shastasaurus, which do not appear in Europe or Spitzbergen. The 
Central European Muschelkalk no doubt also contains one or two 
specific types, and Pessosaurus and Pessopteryx are characteristic of 
Spitzbergen. 

If we turn to other reptile groups that are not adapted to a pelagic 
mode of living in such a high degree as the ichthyosaurians the dis- 
similarities of course become greater. In the Alpine Trias two notho- 
saurians, Pachypleura (Neusticosaurus) from Besano and the some- 
what younger Lariosaurus of Perledo, are found. In the Middle Euro- 
pean Muschelkalk are found numerous nothosaurians and placodonts. 
The marine Trias beds in Spitzbergen also contain several evidently 



72 



University of California Publications in Geology [Vol. 10 



marine labyrinthodonts, 22 and in western North America are found 
thalattosaurians 8 ' 11 to which one nowhere has found any analogy. 

Lastly, I would like to draw attention to a hitherto utterly neg- 
lected region containing marine Triassic saurians, namely, Arctic 
North America, where we have long known that ichthyosaurians are 
to be found. Triassic beds lie exposed on Prince Patrick Island, 
Parry Islands, and on the western side of Ellesmere Land. One or 
more of these islands could, no doubt, be reached by ship, at least 
during favorable years, and from the eastern parts collections could 
be freighted down on sledges across Ellesmere Land, to the eastern 
shore of which one can come with ships by Smith Sound. How 
accessible the occurrences on either side of the northern part of Smith 
Sound are I do not know. 



Transmitted February 25, 1916. 



1916] Wiman: Marine Triassic Reptile Fauna of Spitzbcrgen 73 



LITERATURE 

1. Alessandri, G. De, Studii sui pesei triasici della Lombardia. Mem. Soc. Ital. 

di Sci. Nat., vol. 7, fase. 1, Pavia, 1910. 

2. Baur, G., Ueber den Ursprung der Extremitaten der Ichthyopterygier. Be- 

rieht d. oberrhein. geol. Ver., 20 Verslg., 1887. 

3. Dames, W., Ueber die Ichthyopterygier der Triasformation. Sitzungsber. 

Akad. Berlin, Jahrg. 1895, Bd. 2, p. 1045, Berlin, 1895. 

4. Dollo, L., Globidens Fraasi. Arch, de Biol., vol. 28, p. 609, Liege, 1913. 

5. Fraas, E., Die Ichthyosaurier der siiddeutschen Trias- und Jura-Ablagerungen. 

Verlag der H. Laupp 'schen Buchh., Tubingen, 1891. 

6. Fraas, E., Embryonaler Ichthyosaurus mit Hautbekleidung. Jahresber. d. Ver. 

vaterl. Naturk. in Wiirttemberg, Jahrg. 1911, p. 480, Stuttgart, 1911. 

7. Huene, F. v., Ichthyosaurier der sehwabisehen Trias. Vortrag. Ibid., Jahrg. 

70, 1914. 

8. Merriam, J. C, The thalattosauria. Mem. Calif. Acad. Sc., vol. 5, no. 1, 1905. 

9. Merriam, J. C, Preliminary note on a new marine reptile from the middle 

Triassic of Nevada. Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, no. 5, 
p. 75, Berkeley, 1906. 

10. Merriam, J. C, Triassic ichthyosauria with speeial reference to the American 

forms. Mem. Univ. Calif., vol. 1, no. 1, Berkeley, 1908. 

11. Merriam, J. G, Notes on the osteology of the thalattosaurian genus Neetosaurus. 

Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, no. 13, p. 217, Berkeley, 1908. 

12. Merriam, J. C, The skull and dentition of a primitive iehthyosaurian from 

the Middle Triassic. Ibid., no. 24, p. 381, Berkeley, 1910. 

13. Merriam, J. C, Notes on the relationships of the marine fauna described 

from the Triassic of Spitsbergen by Wiman. Ibid., vol. 6, no. 13, p. 317, 
Berkeley, 1911. 

14. Merriam, J. C, and Bryant, H. G, Notes on the dentition of Omphalosaurus. 

Ibid., no. 14, p. 329, Berkeley, 1911. 

15. Mojsisovics, E., Arktische Triasfaunen. Mem. Acad. Imp. Sc. St. Petersb., 

ser. 7, torn. 33, no. 6, St. Petersburg, 1886. 

16. Nathorst, A. G., Beitriige zur Geologie der Baren-Insel, Spitzbergens und des 

KSnig-Karl-Landes. Bull. Geol. Inst. Upsala, vol. 10, p. 261, Upsala, 1910. 

17. Quenstedt, Fr. A., Handbuch der Petrefactenkunde. 1852. 

18. Eepossi, E., II Mixosauro degli strati Triasici di Besano in Lombardia. Atti 

Soc. Ital. di Sc. Nat., vol. 14, Milano, 1901. 

19. Simionescu, I., lehthyosaurierreste aus der Trias von Dobrogea (Eumanien). 

Bull. Sect. Sci. de 1'Acad. Bourn., annee 1, no. 2, p. 81, Bucarest, 1913. 

20. Wiman, C, Ichthyosaurier aus der Trias Spitzbergens. Bull. Geol. Inst. 

Upsala, vol. 10, p. 124, Upsala, 1910. 

21. Wiman, C, Ueber Mixosaurus cornalianus. Ibid., vol. 11, p. 230, Upsala, 1912. 

22. Wiman, C, Ueber die Stegocephalen aus der Trias Spitzbergens. Ibid., vol. 

13, p. 1, Upsala, 1914. 

23. Wittenburg, P. v., Ueber Werfener-Schichten von Spitsbergen. Bull. Acad. 

Imp. Sc. de St. Petersb., Jahrg. 1912, p. 947, St. Petersburg, 1912. 



/ 

I 

UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 6, pp. 75-85 Issued November 18, 1916 



NEW MAMMALIAN FAUNAS FROM MIOCENE 
SEDIMENTS NEAR TEHACHAPI PASS IN 
THE SOUTHERN SIERRA NEVADA 

BY 

JOHN P. BUWALDA 



UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 




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of Spitzbergen by Wiman, by John C. Merriam. 

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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 6, pp. 75-85 Issued November 18, 1916 



NEW MAMMALIAN FAUNAS FROM MIOCENE 
SEDIMENTS NEAR TEHACHAPI PASS IN 

THE SOUTHERN SIERRA NEVADA^^]^ 

BY 

JOHN P. BUWALDA 



CONTENTS 



PAGE 

Introduction 75 

Occurrence 76 

Phillips Ranch Fauna 77 

Cache Peak Fauna 80 

Eelationships of the Faunas 81 

Geologic Significance of the Faunas 84 

Introduction 

During the past five years expeditions under the direction of the 
Department of Palaeontology of the University of California have 
made considerable collections of Tertiary mammalian fossils in for- 
mations near Barstow and at Bicardo, in the Mojave Desert. Mam- 
malian material has also been obtained in sections containing marine 
formations in the Southern San Joaquin Valley, on the western or 
opposite side of the southern Sierra Nevada. Study of this material 
from the Mojave Desert and the San Joaquin Valley has yielded 
important information regarding the history of mammalian life in 
these regions. With the geologic data obtained it is being made the 
basis for a beginning in the correlation of events in the Tertiary 
palaeontologic and geologic history of the Great Basin and Pacific 
Coast provinces. 

With a view to contributing to the solution of this general problem 
of Cenozoic correlation between the Great Basin and Pacific Coast 



76 University of California Publications in Geology [Vol. 10 



provinces, the writer examined an area of sedimentary deposits near 
Tehachapi Pass, in the southern Sierra Nevada. This area lies directly 
between the San Joaquin Valley and the Mojave Desert. Because of 
its position it seemed probable that its study would yield critical infor- 
mation bearing upon the question of correlation between the two 
provinces. Reconnaissance examinations by the writer in the winter 
of 1912 and in the summer of 1914 had, moreover, suggested the proba- 
bility of the presence of mammalian fossils in the exposures of sedi- 
mentary strata in the Tehachapi area. 

As the result of several weeks' work in the Tehachapi Pass region 
in November and December, 1914, two fossil faunas were secured at 
quite widely separated horizons. More material was obtained in June, 
1915, in the collection of which the writer was ably assisted by Clarence 
L. Moody, James M. Douglas, and Edward Thacher. 

Though the collections are not large, they are thought to contribute 
new information relating to the history of the Mammalia of western 
North America, and bearing on the geologic history of the southern 
Sierra Nevada and adjacent regions. 

This paper is a summary statement of the composition and rela- 
tionships of these faunas. Detailed descriptions of the faunas and a 
discussion of the geologic results are to follow. 

Occurrence 

The Tertiary formations in which the mammalian faunas are found 
in the Tehachapi region are in part an extension of beds first brought 
to notice by Professor Andrew C. Lawson, 1 who described strata ex- 
posed in the vicinity of Monolith and lower Cache Creek, near Teha- 
chapi Pass. 

The formations are included in a section of volcanic and terrestrial 
materials extending over an area of seventy-five to eighty square miles 
or more of the summit region of the southern Sierra northeast of the 
town of Tehachapi. The total thickness of the formations is probably 
not less than four or five thousand feet. Constituting the group are 
basic lava flows, volcanic agglomerates, massive pumiceous tuffs, strati- 
fied ash beds, terrestrial sandstones, clays, cherts, and fanglomerates. 
The fossiliferous horizons are probably stratigraphically near the 
middle of the section. The whole succession of strata records recur- 
rent volcanic activity, with intervening periods of subaerial and lacus- 
tral deposition. The angular fanglomeratic character of the coarser 

i Univ. Calif. Publ., Bull. Dept. Geol., vol. 4, pp. 431-462, 1906. 



1916] Buwalda: Miocene Mammalian Faunas from Tehaehapi Pass 77 



sediments and the similarity of the finer beds to playa lake deposits 
strongly suggest that the climate was arid or semi-arid, rather than 
humid. The presence of palm leaves near the lower of the horizons 
at which mammalian remains were found does not conflict with this 
inference. 

Since their deposition the series of deposits containing the faunas 
have been folded, with dips up to 30 degrees. The tilted strata have 
been in part cut away by erosion, and their deep dissection lias afforded 
excellent opportunity for securing collections of the contained fossil 
remains. The fossils were obtained from badland surfaces, on which 
they lie where the matrix has been blown or washed away, and from 
rocky shelves on the bluffs in which the fossils were embedded. 

The two localities from which the faunas were collected are situ- 
ated about three miles apart. The lower fauna was found in sand- 
stones, containing chert layers, about nine miles northeast of the town 
of Tehaehapi, and one mile northeast of Phillips Ranch, which is on 
Sand Creek, a tributary of Cache Creek. This assemblage may be 
known as the Phillips Ranch fauna. The second or younger fauna 
occurs in coarse sandstones and fine fanglomerates exposed along the 
south fork of upper Cache Creek, about three and one-half miles east 
of Phillips Ranch. This upper mammal-bearing horizon passes under 
Cache Peak on the divide between Cache Creek and Jawbone Canon. 
This will be known as the Cache Peak fauna. Strata of an estimated 
thickness of five hundred feet separate the horizons of the Phillips 
Ranch and Cache Peak faunas. It is quite possible that an uncon- 
formity occurs in the section between the two faunas ; evidence sug- 
gesting an erosion interval was noted in upper Oil Canyon, a tributary 
of Cache Creek from the south. 

The Phillips Ranch fauna was obtained at a single locality ex- 
tending only a few hundred feet along the outcrop of the beds and 
through but fifty or seventy-five feet of the strata. The Cache Peak 
material was collected from exposures distributed over an area perhaps 
two miles long and extending through several hundred feet of beds. 



The collection from the lower horizon near Phillips Ranch includes 
the following forms : 



PHILLIPS RANCH FAUNA 



Merychippns, n. s[ 
Camelkl, large 
Camelid, small 
Moropus, sp. 



Merycodus? sp. 
Carnivore, indet. 
Canid, in<let. 
Felid, indet. 



78 



University of California Publications in Geology [Vol. 10 



The horses of the Phillips Ranch fauna are of a type in or near 
the genus Merychippus, but possibly represent a new subgenus of 
that group less advanced in tooth structure than typical Merychippus. 
They are represented by upper and lower cheek-teeth and by a number 
of limb bones. The upper cheek-teeth are short hypsodont, the height 
being about equal to or a little greater than the transverse diameter 
in well worn teeth. The teeth are small, those in the middle of the 
series ranging from 15.6 to 17.1 mm. in anteroposterior diameter and 
from about 15 to 16.4 nun. transverse diameter. Height of worn teeth 
on the outer side is 15 to 18 mm., on inner side 10.2 to 12.2 m. They 
are relatively narrow transversely compared with the teeth of typical 
species of Merychippus. The outer and inner faces are not approxi- 
mately parallel as in strictly prismatic teeth, but approach each other 
somewhat toward the summits of the teeth. The crowns are slightly 
curved. They are well cemented, but the cement covering is not heavy. 
The outer faces of paracone and metacone are flat or have a very faint 
median rib. The mesostyle is prominent, narrow, and may be of nearly 
equal width from base to summit of tooth, or may flare slightly at the 
base. The protoconule and metaconule are slightly larger than proto- 
cone and hypocone. The protoconule is slightly crescentic and is 
broadly connected with the oval protocone. The metaloph is com- 
pletely connected with ectoloph, but is usually not connected with 
protoloph because of imperfect development of the posterior horn of 
the protoconule. The fossettes are well cemented, with one or two 
crinkles in the enamel borders. The prefossette is usually open on the 
median or inner border between protoloph and metaloph. The post- 
fossette is sometimes closed and sometimes open between bypocone 
and hypostyle. 

Tbe upper cheek-teeth are more advanced than those of Parahippus 
and the other genera of the Anchitheriinae in the greater height of 
the crowns and in their prismatic form, in their strong cementation, 
in the relatively large size of protoconule and metaconule compared 
with protocone and hypocone, and in the tendency to close the fos- 
settes. They are relatively primitive compared with described forms 
of Merychippus in their small size, shorter crowns, subequality in size 
of protocone and protoconule, in the imperfect development of the 
posterior horn of the protoconule, and in the general openness of the 
fossettes on the inner side. 

The characters are in a measure those assigned by Gidley 2 to 
hypothetical genera of a group "C" of division "Anchitheriinae 

2 Gidley, J. W., Bull. Am. Mus. Nat. Hist., vol. 23, p. 868, 1907. 



1916] Buimlda: Miocene Mammalian Faunas from TehachapiPass 79 



Leidy": "Inner coimles (pr and hy) smaller than median conules 
(pi and ml), protocomile semi-crescentic ; partially or completely 
united with the metaloph ; . . . " 

The lower cheek-teeth of this equid form are all of one type, char- 
acterized by being distinctly hypsodont, and well cemented. Their 
length is approximately one to one and one-half times their antero- 
posterior diameter. The metaconid-metastylid column is well devel- 
oped. The marked groove between the metaconid and metastylid per- 
sists nearly to the base of the tooth. The lower cheek-teeth seem in 
some respects more advanced than the upper, but certainly represent 
the same form, as the upper and lower teeth of the same individual 
have been found together. 

In one specimen (no. 21692) lower milk teeth are present in the 
jaw with the permanent teeth. The deciduous teeth are of the short- 
crowned type and bear a thin cement layer. 

With the horse teeth are three astragali and scattered limb bones 
representing small forms. One of the three astragali is much smaller 
than the others and possibly represents a type distinct from that 
indicated by the other material. 

The camels of the Phillips Ranch fauna are known from cheek- 
teeth, an astragalus, a distal portion of a radius, a distal portion of a 
tibia, and by a number of foot bones. The material probably does not 
permit of specific determination, but difference in the size of the teeth 
suggests that a large and a small species of camel are present. 

Moropus is indicated in the assemblage of species by a portion of 
a lower jaw containing three premolars and a molar, all little worn. 
Compared with Moropus elatus Marsh, the teeth in this jaw are con- 
siderably smaller and are relatively narrower transversely. 

An incomplete calcaneum closely resembles that of the antelope- 
like Merycodus. 

A toothless carnivore jaw represents a small form which is probably 
not generically determinable. 

A part of a lower jaw, probably of a canid, and a portion of a tooth, 
apparently a felid, likewise do not admit of exact identification. 

The evidence as to age of the Phillips Ranch fauna is furnished 
principally by the horse material. The Merychippus is possibly so 
primitive that it should be set off as a new subgenus. Merychippus 
is usually held to range from middle Miocene to early Pliocene. It 
appears that this faunal stage is not younger than middle Miocene and 
may represent a somewhat earlier stage of that period. 



80 University of California Publications in Geology [Vol. 10 



CACHE PEAK FAUNA 

The Cache Peak fauna includes the following forms: 

Merychippus, n. sp., a Meryeoehoerus( ?) , sp. 

Merychippus, n. sp., b Dromomeryx, sp. 

Hypohippus, sp. Merycodus, sp. 

Camelid, sp., a • Felid, sp. 

Camelid, sp., b 

Of the three forms of horses only one is represented by sufficient 
material to make possible a full study. Of this type there were ob- 
tained a nearly complete skull (no. 22254, Univ. Calif. Loc. 2735) with 
complete upper cheek dentition, a complete femur, complete meta- 
podial region with lateral elements and phalangeal series, and the ex- 
tremities of a number of other limb bones. No lower teeth of this 
individual were found. 

The notable characters of the dentition of this specimen are as 
follows : Upper cheek-teeth short hypsodont and well cemented. 
Mesostyle strongly developed. Protocone flat oval in cross-section and 
slightly smaller than the protoconule, distinctly connected with the 
protoconule in every tooth in the skull. Protoconule and metaconule 
not notably creseentic. Postfossette closed in all the teeth ; prefossette 
closed on the inner or median side in seven of the twelve teeth. 

Several other upper cheek-teeth from the Cache Peak horizon, some 
unworn, are of the same type as those of no. 22254, and exhibit no 
new characters. In the course of wear the protocone of these teeth 
would be disconnected from the protoconule until approximately the 
upper half of the tooth had been worn away. 

Several lower cheek-teeth in the collections, presumably represent- 
ing the form seen in no. 22254, are also quite heavily cemented. 

The type of horse represented by these upper and lower cheek-teeth 
is certainly to be characterized as a species of Merychippus as this 
group is at present defined, and is not one of the most primitive 
members of the group. 

The second form of horse in the Cache Peak fauna is known only 
by parts of three upper cheek-teeth, two of which fortunately exhibit 
the protocone-protoconule relation. These teeth are badly worn, but 
the crowns appear to have been rather short hypsodont, well cemented, 
and somewhat curved. The most notable feature is the fact that the 
protocone as shown in no. 21693 is widely disconnected from the proto- 
conule to the very base of the tooth, and that it is short oval in cross- 
section. The protoconule in this specimen is distinctly larger than 



1916] Buwalda: Miocene Mammalian Faunas from Tehachapi Pass 81 



the protocone, is markedly crescentic in outline, and is connected with 
the metaloph. The last three characters are among those which set off 
the Mcrychippus group from the earlier horses. So far as can be 
judged from the scanty material, this form should be included within 
the genus Mcrychippus, but the disconnected protocone indicates that 
it probably lies within that division of the genus leading toward the 
Hipparion stock rather than within the division which probably gave 
rise to Protohippus, PUoMppus, and other forms with connected pro- 
tocone. 

The Hypohippus material consists of three upper cheek-teeth. The 
advanced state of wear will probably not permit the safe reference of 
the form represented by the teeth to any of the described species of 
Hypohippus. 

The collection from the Cache Peak horizon includes a considerable 
amount of camel material, consisting of imperfect limb bones, with a 
few parts of teeth. The remains indicate the presence of at least two 
forms. Fragmentary teeth and some of the limb bones represent a 
species near Procamelus. Certain of the other parts, such as a crushed 
proximal extremity of a metapodial and two imperfect astragali, repre- 
sent a camel decidedly larger than the first species mentioned. 

Of the two teeth indicating the presence of an oreodont in the 
fauna one is presumably Mcrycochocrus ; the other may be generically 
distinct. 

The antelope-like Dromomeryx is represented in the Cache Peak 
fauna by two lower teeth. While it is not desirable to attempt a 
specific determination with such scanty material, the characters of the 
genus are well shown in the accessory median tubercle, the accessory 
anterior ridge developed from the cingulum, and in the roughened 
surface of the enamel. The ' 1 Palaeomeryx fold" on the anterior ex- 
ternal crescent is shown on one of the teeth. Dromomeryx has been 
reported from middle Miocene to early Pliocene. 

The fragmentary Merycodus material indicates a small species of 
that genus. This form may be the same as that occurring in the 
Barstow fauna. 

A felid is known in the fauna by the distal portion of a meta- 
carpal or metatarsal. 

RELATIONSHIPS OF THE FAUNAS 
A comparison of the Phillips Ranch and Cache Peak faunas must 
at present be based largely upon the horses represented in the two 



82 University of California Publications in Geology [ VoL - 10 



collections. Moropus occurs only in the former fauna, while Meryco- 
choerus(f) and Dromomeryx are found only in the latter, hut the 
collections are not sufficiently large to make the absence of a form 
from one fauna and its presence in the other significant. Merycodus 
is present in the collections from both localities, but the material is too 
scanty to allow an accurate comparison. 

Of the horses, the species from the Phillips Ranch horizon has much 
smaller and much more primitive cheek-teeth than either of the forms 
in the Cache Peak fauna. The horse astragali from the Phillips Ranch 
horizon are all of a smaller type, while there are in the collections from 
the upper horizon astragali of a larger type as well. 

The evidence of the camel material is not emphatic, but the larger 
size of most of the camel teeth and foot parts in the Cache Peak fauna 
tends to confirm the view that this assemblage represents a more 
advanced stage. 

The Phillips Ranch fauna is quite certainly considerably older and 
less advanced than the assemblage from the Cache Peak horizon. 

In considering the relations of the Phillips Ranch and Cache Peak 
faunas to other groups it seems desirable to compare them with faunas 
known from neighboring areas. In the Mojave Desert the Ricardo 
fauna, known from considerable collections to be of approximately 
lower Pliocene age, occurs about twenty miles to the northeast ; the 
Barstow fauna, also well represented by material and of approxi- 
mately upper Miocene age, is found about eighty miles to the east. 
In the southern San Joaquin Valley on the opposite side of the south- 
ern Sierra a meager collection obtained in the Tejon Hills is of ap- 
proximately very late Miocene or lower Pliocene age. 

The species of Merychippus found in the Phillips Ranch fauna is 
very different from any species found in the Barstow upper Miocene 
collection, being much more primitive. The camels do not permit of 
an exact comparison because of scantiness of the Phillips Ranch 
material, but they appear to be different. The species of Merycodus 
may be the same as that from Barstow, but with the material at hand 
a certain determination cannot be made. 

The horse material from Phillips Ranch resembles still less any of 
the horses found in the Ricardo fauna, being much more primitive. 
It is likewise less advanced than the horse species obtained in the 
Tejon Hills in the southern San Joaquin Valley. 

The Phillips Ranch fauna certainly represents a stage of evolu- 
tionary development much earlier than the Barstow, Ricardo and 
Tejon Hills faunas. 



1916] Buwalda: Miocene Mammalian Faunas from Tehachapi Pass 83 

The horses of the Phillips Ranch fauna appear more primitive 
than those of either the Mascall or the Virgin Valley. They may be 
of a middle Miocene stage, but older than the stage of either the 
Mascall or the Virgin Valley. The lower, or Phillips Ranch horizon, 
appears to represent the oldest stage in the development of mammalian 
life above the Oligocene known thus far in the region west of the 
Wasatch. 

The Cache Peak fauna has been stated to be more advanced than 
that from near Phillips Ranch. The Hypohippus of the Cache Peak 
assemblage is probably specifically distinct from that found at Bar- 
stow. The complete skull with dentition representing Merychippus 
differs somewhat in the details of the facial region and in its dentition 
from Merychippus calamarius, a common form at Barstow, but ap- 
pears to be quite near that species. The Hipparion-like horse teeth 
of the Cache Peak fauna have the protocone more distinctly separated 
than it is in the nearest allied type in the Barstow fauna ; this wide 
separation is probably an advanced character. On the other hand, 
the Barstow fauna contains horses which have longer and heavier lower 
molars than any found in the Cache Peak assemblage. 

The Dromomeryx teeth from the Cache Peak horizon seem consid- 
erably shorter and less advanced than the form found at Barstow. 
The Merycodus cannot be compared satisfactorily. The Merycochoerus 
form may be different, but the material is too fragmentary to permit 
a certain comparison. 

Comparing the Cache Peak with the Ricardo, no form is known to 
be common to the two faunas, although the Merycodus may be the 
same. The horses in the lower part of the Ricardo section are mainly 
very advanced types of Pliohippus and Hipparion. 

The horses obtained in the Cache Peak horizon are all different 
from those so far known from the Tejon Hills, and probably represent 
a stage somewhat older. 

The Cache Peak fauna is probably considerably older than the 
Ricardo, probably somewhat older than the Tejon Hills, but probably 
does not differ greatly in age from the Barstow. 

The Cache Peak fauna represents a stage in advance of that found 
at Phillips Ranch. The Cache Peak fauna may be late middle Miocene 
or upper Miocene ; it may furnish a transition stage between the 
Phillips Ranch and the Barstow faunas, but it is much nearer to the 
Barstow than to the Phillips Ranch. 



84 University of California Publications in Geology [Vol. 10 



GEOLOGIC SIGNIFICANCE OF THE FAUNAS 

The faunas, consisting as they do in large part of horses, camels, 
and antelope-like forms, point to a plains or open valley environment 
in this region in middle Miocene time. 

The deposits in which the faunas occur are of types which suggest 
that they were laid down under subaerial conditions as waste slope and 
playa lake deposits ; the evidence for this view is corroborated by the 
occurrence of the mammalian remains, which are usually scattered and 
frequently much gnawed by rodents. The angularity of the coarser 
terrestrial deposits precludes their fluviatile origin, and the lack of 
classification and bedding in the fine materials militates against their 
being in any large measure of truly lacustrine origin. The faunas 
and the formations in which they occur thus indicate that the climate 
was one of semi-aridity or aridity. Fossil wood and palm leaves at 
one or more horizons probably do not negative this view. 

The age of the faunas being established as approximately middle 
and upper Miocene respectively, stratigraphic relations indicate that 
important crustal movements occurred in this region between Jurassic 
and middle Miocene time and in post-middle-Miocene time. 

The movements subsequent to the Jurassic and antecedent to the 
middle Miocene are indicated by the relation of the mammal-bearing 
group to a succession of sediments which lie with marked unconformity 
below these strata and rest unconformably on the plutonic rocks of 
presumable Jurassic age. This lower sedimentary series, which is well 
exposed along lower Oil Canon, has been deformed to the extent that 
the strata attain a vertical position over much of the area in which 
they are exposed. It is not improbable that deformative movements 
affected the territory immediately previously to the deposition of the 
mammal-bearing group, inasmuch as the topography on which these 
beds were laid down was one of some relief and indicates active erosion 
immediately preceding their deposition. 

The crustal movements subsequent to middle Miocene time in the 
Tehachapi Pass region are evidenced by the folding which the mammal- 
bearing group has suffered since its deposition ; dips of twenty to thirty 
degrees are common in the strata. Following this folding, erosion 
cut away no small part of the total mass of the accumulated sediments 
and probably produced on the region a land surface of gentle relief. 
The latest diastrophic event was the faulting along the southeastern 
base of the present range, by which the mountain area Avas displaced 



1916] Buwalda: Miocene Mammalian Faunas from Tehaehapi Pass 85 



vertically 2500 to 3000 feet with respect to the adjacent Mojave Desert 
area. This zone of displacement fractured the strata containing the 
middle Miocene mammalian remains, so that if there were no other 
basis for determining the date of the great displacement which gave 
the southern Sierra Nevada its present orographic features, the lower 
limit in time would be denned by the upper Miocene age of the younger 
of the two faunas. This would indicate that the faulting occurred in 
late Miocene or post-Miocene time. This fact is of interest when it is 
recalled that some geologists have set earlier dates for the faulting by 
which the northern Sierra Nevada attained its present elevation above 
the Great Basin. 

Transmitted April 9, 1915. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 7, pp. 87-109, 23 text-figures Issued November I, 1916 



AN AMERICAN PLIOCENE BEAR 



BY 

JOHN C. MERRIAM, 
CHESTER STOCK, and CLARENCE L. MOODY 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 7, pp. 87-109, 23 text-figures Issued November 1, 1916 



AN AMERICAN PLIOCENE BEAR 

BY 

JOHN C. MEREIAM, 
CHESTER STOCK, and CLARENCE L. MOODY 



CONTENTS 

PAGE 



Introduction 87 

Occurrence - - - 88 

Dentition 90 

Skeletal Elements 97 

Relationships 105 



INTRODUCTION 

Although the bear group is well known in some of the latest 
Cenozoic faunas of the Western Hemisphere, the one or two occur- 
rences of very fragmentary material reported to represent this family 
in American deposits older than Pleistocene have been considered 
doubtful. In the Old World, members of the Ursidae are found in 
formations ranging from Miocene to Recent, and in view of available 
evidence it is assumed generally that the New World bears are com- 
paratively recent immigrants, the earliest arrivals having come from 
Asia to North America near the beginning of Pleistocene time. 

The North American Pleistocene bears comprise two groups ; the 
Ursus type, represented by forms closely related to existing species of 
this continent; and the peculiar short-faced arctotheres, having no 
living representatives in North America, but closely related to the 
spectacle bear of South America. In the Pleistocene of South America 
Arctotherium is known by several species, but Ursus is not represented. 
There is then apparent basis for the theory that Arctotherium arrived 
in North America in advance of bears of the Ursus type and reached 




88 University of California Publications in Geology [Vol. 10 



South America before TJrsus crossed from the Old World. If this 
view expresses the history of migration of bears in America, remains 
of Arctotherium, or of a type ancestral to this genus, might be expected 
in earliest Pleistocene or Pliocene deposits of North America. The 
absence of Arctotherium and of well authenticated remains of near 
relatives of this division of the bear group from North American 
deposits older than those containing Ursus has sometimes been inter- 
preted to indicate the migration of Arctotherium, or of its ancestors, 
to South America by some route other than that through North 
America. 

In the course of a special study of the later Tertiary deposits of 
eastern Oregon carried on by the Department of Palaeontology of 
the University of California in the summer of 3 016, remains of a 
member of the bear group were discovered by Chester Stock and 
Clarence L. Moody in beds of the Rattlesnake Pliocene of the John 
Day region. The significance of this discovery, especially with rela- 
tion to other studies on correlation and migration of Tertiary mammal 
faunas, makes desirable a statement of the evidence in advance of a 
full report on the Rattlesnake fauna. 

OCCURRENCE 

Remains of the Pliocene bear (no. 22362) were found in the Rattle- 
snake formation exposed on the East Fork of the John Day River 
in northeastern Oregon. The locality is situated near the center of 
N.W. 14 sec. 30, T. 12 S.. R. 26 B. v Willamette Base Line and 
Meridian, Grant County. Oregon, approximately five and one-half 
miles west of Dayville, and not over three-fourths of a mile south 
of the type section of the Rattlesnake formation. The specimen was 
found on a low ridge between Rattlesnake Creek and Little Rattle- 
snake Creek. 

In the typical area the Rattlesnake formation is tilted at an angle 
of approximately five degrees and rests upon a basement formed 
by sharply deformed, truncated strata of the Mascall Middle Miocene. 
The present canyon of the John Day River cuts through the basin 
of accumulation of the Rattlesnake." In the bottom of this canyon 
Pleistocene mammal remains are found in terrace deposits laid down 
after the canyon had attained approximately its present form. The 
stage of the Rattlesnake is thus limited on one side by antecedent 
Middle Miocene and by the period of deformation and extensive erosion 
intervening between deposition of the Mascall and beginning accumu- 



1916] Merriam-Stock— Moody : An American Pliocene Bear 



89 



lation of the Rattlesnake. On the other side this stage is limited by 
the date of subsequent Pleistocene terraces and the period of canyon 
cutting intervening between the close of the Rattlesnake and begin- 
ning accumulation of the terrace deposits. 

The known mammalian fauna of the Rattlesnake comprises between 
twenty and thirty species. The available representation will be fully 
discussed in an early publication. The horses are presumably the 
most important elements of the fauna for purposes of palaeontologic 
and geologic correlation. The Equidae are represented by species of 
the Hipparion and Pliohippus groups having their nearest relatives 
in beds referred to the early Pliocene of the Great Basin and Pacific 
Coast provinces. The view that the Rattlesnake fauna is related to 
that of the Thousand Creek Pliocene in Nevada receives support 
through the discovery of a horn-core of the peculiar antelope 
Sphenophalos in the Rattlesnake, in the course of the past season's 
work. This antelope has heretofore been known only from the 
Thousand Creek, where it occurs in association with twisted-horn 
antelopes of the Ilingoceros type. 

In the locality at which the bear remains were found the Rattle- 
snake formation consists principally of a series of cross-bedded gravels 
alternating with varicolored tuffs and sands. A persistent rhyolite 
flow occurs at a high horizon in the formation. Pebbles in any single 
stratum are usually of comparable dimensions, but sharp changes occur 
in passing from one bed to another. Thus a stratum with bowlders 
attaining a diameter of one foot may immediately overlie a bed in 
which the largest pebbles have a diameter of not more than one-half 
inch. It was in a layer of the finer gravel that the bear remains were 
discovered. The bed seems to be lenticular, but this appearance may 
be due to occurrence of the gravels on the summit of a ridge. Maseall 
Miocene is exposed in the bed of Rattlesnake Creek to the north of 
the ridge upon which the gravels were found. This ridge has an 
approximate elevation of 150 feet above the level of the stream, 
thus placing the horizon at which the bear remains occurred well up 
in the Rattlesnake section. The erosion of Rattlesnake and Little 
Rattlesnake creeks has removed a large part of the formation south 
of the course of the former stream, and the section is known to be 
thicker toward the south. It has therefore not been found possible 
to ascertain the exact distance below the summit of the section repre- 
sented by the bed in which the bear specimen was found. This horizon 
is believed to be stratigraphically within the limits of about 100 feet 



90 University of California Publications in Geology [Vol. 10 



below the top of the rhyolite cap which forms the summit of the 
section at the type locality of the Rattlesnake. 

The material representing the Pliocene bear includes the most 
important parts of the dentition, with six or seven representative 
elements of the limbs. There is good reason for considering that all 
of these specimens are derived from one individual. The preservation 
of the bones and teeth corresponds in general to that of other mammal 
remains obtained in the type section of the Rattlesnake formation. 

DENTITION 

The dentition of specimen no. 22362 from the Rattlesnake Pliocene 
includes practically all essential elements. Prom the upper jaws there 
are represented P, P, C, P-, and M-. The first upper molar is 
the only superior tooth of importance lacking. Prom the mandible 
only the canines and were found. "While it is to be regretted that 
the lower earnassial is not available, it should be noted that the forms 
most nearly related to this particular type show less variation in M T 
than in P-, M-, and Mtt, all of which are at hand. The teeth present 
illustrate so fully the characters of the dentition as a whole that it 
is possible to make those comparative studies most important in 
determination of the relationships of this animal. 

The two upper incisors present are much worn. So far as 
can be determined, they are of approximately the type seen in 
Arctothcrium, lint are larger than the corresponding elements in A. 
simum of the California Pleistocene. 




Figs. 1 ami 2. hidarctosf ?) oregonensis, n. sp. Canine teeth, no. 22362, lateral 
view, X Vo. Fig. 1, upper canine; fig. 2, lower canine. Rattlesnake formation, 
John Day Valley, Oregon. 



1916] Merriam-Stock-Moody : An American Pliocene Bear 91 



The large, heavy-fanged canines (figs. 1 and 2) are of the char- 
acteristic ursid type. The crowns of the upper canines have 
dimensions and proportions near those of A. si inn in of Potter Creek 
Cave. The roots may be larger relative to the size of the crown 
in the Rattlesnake specimen, but are not thicker in either transverse 
or anteroposterior diameter. In the lower canines, as in A. sun ion, 
the crowns are sharply concave on the posterior side. As in the 
upper canines, the crowns are near the size of those in A. si nut in, but 
the roots seem relatively large. 

Pi shows a form closely approaching that in the corresponding 
tooth of A. si nut m. This tooth (fig. 3) has a simple single root; and 
the crown consists of a single cusp, which extends 
to the anterior and posterior borders of the tooth 
in a, well-marked longitudinal ridge or crest. Tin 1 
anterior ridge is noticeably convex on the outer 
side, and drops off abruptly or may be concave on 
the median side. A distinctly marked ridge of the 
cingnlum on the antero-internal side unites an- 
teriorly with the principal crest. 

Fortunately both the right and left upper car- 
nassials (P-) are represented. These teeth (figs. 
4r? to 4c) are large and unusually well developed 
for members of the Ursidae. They differ markedly 
from all specimens of Ursus and Arctotherium 
known to the writers, and approach closely the type of P- known in 
the several species of Ryaenarctos (figs. 5 to 7) . In the Oregon species 
the protocone is slightly larger than the tritocone. The deuterocone 
is very large, approximating in its cross-section the size of the proto- 
cone; and is situated so far forward that its anterior border is not 
posterior to the corresponding border of the protocone as in Visits 
and Arctotherium. A large protostyle is present. The tooth is 
distinctly three-rooted, a large and widely divergent root supporting 
the deuterocone. The outer contour of the tooth shows a distinct 
concavity of the cingulum opposite the posterior side of the protocone. 

Pi differs from the corresponding tooth of Arctotherium in the 
relatively large size of the deuterocone ; in the support of the deutero- 
cone upon a distinct, widely diverging inner or third root; in the 
situation of the deuterocone as far forward as the protocone ; and 
in the presence of a large, distinctly separated protostyle. In all of 
the characters in which this tooth differs from Arctotherium it re- 




Fig, 3. Indaro- 
tos(?) oregonensis, 
n.sp. Pi, no. 22362, 
inner and occlusal 
views, natural 
size. Kattlesnake 
formation, J o h n 
Day Valley, Ore- 
gon. 



92 University of California Publications in Geology [Vol. 10 



sembles Hyaenarctos. If isolated from other material, P- would 
certainly be considered as representing Hyaenarctos rather than the 
Arctotherium type. 




7 



Figs. 4a to 4c. Indarctos(P) oregonensis, n. sp. P*, no. 22362, natural size. 
Fig. 4a, occlusal view; fig. 4b, outer view; fig. 4c, inner view. Rattlesnake for- 
mation, John Day Valley, Oregon. 

Fig. •">. II i/tif'ini t'ctos insignia P. Gervais. P 1 , occlusal view, natural size. 
Montpellier, France. (After Gervais.) 

Fig. 6. Hyaenarctos palaeindicus Lydekker. P±, occlusal view, natural size. 
Siwalik beds, India. (After Lydekker.) 

Fig. 7. Hyaenarctos insignis P. Gervais. P 1 , inner view, natural size. Mont- 
pellier, France. (After Gervais.) 

The upper carnassial of no. 22362 may be more primitive than 
that of Arctotherium in the anterior position of the deuterocone, and 
is more specialized in the presence of a large protostyle. In the 
Oregon form the anterior border of the deuterocone is situated approx- 
imately as far forward as the anterior border of the protocone, and 

i Blainville, H. M. D., Osteographie des mammiferes, Atlas 2, pi, 12, 1864. 
■ Pilgrim, Guv E., Records, Geological Survey of India, vol. 44, part 3, pp. 
225-233,' pi. 20, 1914. 



1916] Merriam— Stock-Moody : An American Pliocene Bear 



93 



in Hyaenarctos the deuteroeone tends to take the same position. In 
Arctotherium, and in bears of the JJrsus type, the deuteroeone is 
shifted far back and away from what is considered a normal position 
of this tubercle in the modern Carnivora, and is commonly situated 
opposite the notch between proflocone and tritocone. The protostyle, 
which is so largely developed in the Oregon specimen and in 
Hyaenarctos, may be suggested in some arctothere specimens, and is 
figured by Blainville 1 in his illustration of the dentition of Tremarctos 
ornatus, the Recent South American relative of the arctotheres. It 
is therefore possible that a protostyle was at one time present on 
P* of Arctotherium. 

The posterior upper molars (M-) (figs. 8a to 9) of the bear from 
the Rattlesnake beds most nearly resemble those of the ursid type 
described by Pilgrim 2 from the middle or upper Siwalik beds of 
India under the name of Indarctos salmontanus (fig. 12). M= of 
specimen 22362 resembles the type of I. salmontanus in its unusual 
relation of width to anteroposterior diameter, and in the stage of 
development of the heel. The anteroposterior and transverse diam- 
eters are almost identical with those of the type of /. salmontanus. 
The heel is a trifle longer in the Oregon specimen, but tends to be 
slightly wider in the Indian form. The difference in width of heel is 
possibly due in some part to difference in stage of wear in the speci- 
mens compared. As in I. salmontanus, the paracone and metacone of 
no. 22362 are clearly defined, the paracone being considerably larger 
than the metacone. In /. salmontanus the antero-internal region 
of the tooth consists of a large ridge divided into two tubercles of 
which the anterior is the larger. In the Oregon specimen the heavy 
antero-internal ridge is present, but the teeth are too much worn 
to show distinctly whether this area was divided into two elements. 
On the left tooth such a separation is suggested. In no. 22362. as 
in /. salmontanus, there is evidence of a large tubercle immediately 
behind the antero-internal ridge, corresponding evidently to the 
hypocone. This tubercle appears somewhat larger in Pilgrim's figure 
of I. salmontanus than it is in the left tooth of no. 22362. On the 
right tooth the hypocone may have been somewhat larger. The ex- 
treme posterior end of the heel consists of a transverse ridge which is 
largely worn down. 

The proportions of the various areas of the tooth in no. 22362 
are near those of the type of Indarctos. The anteroposterior diameter 
of the paracone is slightly less than it measures on Pilgrim's figure of 



94 University of California Publications in Geology [Vol. 10 



/. salmontanus. The distance from the posterior end of the paraeone 
to the posterior end of the tooth is slightly greater in no. 22362, as 
is also the distance from the middle of the metacone to the posterior 
end of the tooth. The distance from the middle of the metacone to 
the anterior end of the tooth is greater in I. salmontanus. 




10 11 12 



Figs. 8« to 9. Indarctos( ?) oregonensis, n. sp. M- of right and left sides, 
no. 22362, natural size. Fig. 8a, of left side, outer view; fig. 8b, M 2 of left 
side, occlusal view; fig. 9, M- of right side, occlusal view. Rattlesnake forma- 
tion, John Day Valley, Oregon. 

Fig. 10. Hyaenarctos sivalensis Falc. and Caut. M-, occlusal view, natural 
size. Siwalik beds, India. (After Lydekker.) 

Fig. 11. Hyaenarctos punjabiensis Lydekker. M-, occlusal view, natural 
size. Siwalik beds, India. (After Lydekker.) 

Fig. 12. Indarctos salmontanus Pilgrim. M 2 of type specimen, occlusal view, 
natural size. Siwalik beds, India. (After Pilgrim.) 



1916] Merriam-Stock— Moody : An American Pliocene Bear 95 

Considering that in no. 22362 M- is considerably worn, and allow- 
ing for individual variation, the resemblances between the Oregon 
specimen and the type of I. salmontanus are close. Small differences, 
such as the more distinctly circular cross-section of the metacone, the 
smaller hypocone, .slightly longer heel, and wider trigon region in 
the Oregon form, suggest specific distinction such as would be expected 
in individuals so widely separated geographically. 

The characters of M- in the Oregon form, and in Inclarctos salmon- 
la n us, approach those of Hyaenarctos excepting in relative elongation 
of the heel. The two outer cusps of M- in Hyaenarctos may show 
somewhat stronger lateral compression than is noted in the Oregon 
form. The antero-internal ridge in Hyaenarctos may apparently show 
almost no separation into two divisions, or may be very distinctly 
divided as in H. palaeindicus, in which the hypocone region is imper- 
fectly developed. In H. punjabiensis (fig. 11) an incipient heel is 
clearly shown, though it is much less pronounced than in Imlarctos. 
As has been suggested by Pilgrim, an intermediate stage between the 
form seen in H. punjabiensis and that in the type of 7. salmontanus 
might connect the two groups so closely that generic separation would 
be difficult if not impossible. 

M- of the Rattlesnake specimen is distinguished from that of 
Arctotherium by its greater width and much shorter talon. In 
Arctotherium the primitive quadritubercular portion of the tooth is 
longer anteroposterior^ and the heel is much longer. The arrange- 
ment of the tubercles is much the .same in the two types, hut the 
tubercles show stronger lateral compression in Arctotherium. 

The arrangement of the roots supporting M- in the Oregon speci- 
men differs somewhat from that in Arctotherium simum. In no. 22362 
(fig. 8rt) there are two distinct external roots supporting the paracone 
and metacone regions. These roots in both available teeth are dis- 
tinct, but are not widely separated. The inner and posterior regions 
of these teeth are supported by a large, broad root evidently composed 
of two parts, one of which supports the protocone region and the other 
originates above the hypocone and the region behind it. 

In Arctotherium there are also evidently four original root 
elements, but the roots beneath the paracone and metacone tend to 
diverge widely, the element above the metacone being in some cases 
united with the posterior root supporting the heel. In Arctotherium 
the root supporting the protocone may or may not unite with the root 
above the heel. In the type of Imlarctos salmontanus the roots are 
not exposed. 



in; 



University of California Publications in Geology [Vol.10 



M7, the only representative of the lower cheek-tooth dentition, is 
unfortunately so much worn that it illustrates comparatively few 
characters of the tuberculation (fig. 13). It is distinguished from 
the corresponding element in the dentition of Hyaenarctos and of 
certain forms of Arctotherinm by the relative proportions of the 
trigonid and talonid regions. In the Oregon specimen the antero- 
posterior diameter of trigonid and talonid are, as nearly as can be 
determined, approximately equal. In Hyaenarctos, as is indicated by 
the measurements below, the talonid may have an anteroposterior 
diameter near one-half that of the trigonid. In Arctotherium simum 
the functional talonid may be longer than the trigonid. In some of 
the South American arctotheres, as in Pararctotherium enectum 



Fig. 13. Indarctos(P) oregonensis, n. sp. Mj, no. 22362, occlusal view, natural 
size. Rattlesnake formation, John Day Valley, Oregon. 

Fig. 14. Hyaenarctos punjdbiensis ? Lydekker. Mj, occlusal view, natural 
size. Siwalik beds, India. (After Lydekker.) 

Ameghino, the proportions are as in A. simum; in others, as in A. 
triiu/ti Ameghino. the talonid is relatively short. The increase in 
length of the heel region in A. simum is evidently related to the 
increase in area of M-, as the talonid of articulates with the 
trigonid portion of M-. 

The tuberculation of ^Sl-, represents only the inner side of the 
tooth, on which is shown the relatively high region occupied by the 
metaconid, and the lower more or less basin-like talonid region. The 
talonid possessed a rather wide hypoconid ridge, and two smaller cusps 
on the inner border a.s in Hyaenarctos. 

The crown of M 5 is supported upon two roots of which the posterior 
is the larger. 





13 



14 



1916] 



M < rriam-Stock-Moody : 



An American Pliocene Bear 



97 



Measurements of Dentition 

No. 22362 

C, upper, anteroposterior diameter at base of enamel a29.8mm. 

C, upper, transverse diameter at base of enamel 20.0 

C, upper, length of root, measured along posterior border 76.7 

C, lower, anteroposterior diameter at base of enamel 30.0 

C, lower, transverse diameter at base of enamel 0.21.3 

C, lower, length of root, measured along posterior border 73.8 

P-, anteroposterior diameter 12.4 

P 1 , transverse diameter 7.1 

No. 22362 No. 22362 Indarctos 

Left side Right side salmontanus 

Pi, anteroposterior diameter measured along 

outer side 31.7 mm. 31.0 

P^, width across deuteroeone 22.6 o20.9 

P 1 , anteroposterior diameter of protocone at 

base 14.1 13.0 

P 1 , anteroposterior diameter of protostj'le..-. 4.7 4.6 

M-, greatest anteroposterior diameter 35.3 35.2 35 (35.5*) 

M-, anterior end of tooth to posterior end 

of paraeone 13.8 14.0 14.8* 

M-, posterior end of paraeone to posterior 

end of tooth 21.5 21.2 20.9* 

M-, anterior end of tooth to middle of meta- 

cone 17.8 17.5 19.8* 

M-, middle of metacone to posterior end of 

tooth 17.5 17.6 15.7* 

M-, width of tooth across paraeone 26.8 27.2 27.0 

M-, width of tooth across metacone 24.6 24.0 25.2* 

M-. anterior side of hypocone to posterior 

end of tooth 17.6 15.6 15.4* 

Length of M- compared with width of MX. 1.31% 1.29% 1.29% 



M;, anteroposterior diameter 32.0 mm. 30.4 

M5, anteroposterior diameter of trigonid 15.8 14.9 
Mg, anteroposterior diameter of func- 
tional talonid region 16.2 15.5 

M*, transverse diameter across talonid— .a21.3 18.4 
a, approximate. 

* Measurements taken on Pilgrim's figure of M-. 



A. simum Hyaenarctos Hvaenarctos ? 

No. 22362 No. 3004 punjabiensis ? palaeindicus 

30.5 30.0 

19.0 16.5 



1 1 .5 
19.3 



13.5 
19.2 



SKELETAL ELEMENTS 

The skeleton of no. 22362 is represented by the greater part of 
the humerus, half of the ulna, a fifth metacarpal, the navicular and 
cuboid, a second metatarsal, and several phalanges. 

The right humerus, the first element of the Pliocene bear to be 
discovered, is nearly complete. A portion of the distal end had 
rotted away, and a small part of the proximal end is missing. This 



98 University of California Publications in Geology ITol. 10 



element (figs. 15a to 15c) is slightly longer and considerably more 
massive than that of specimens of Aretotheriuni simum from Potter 
Creek Cave and from Bancho La Brea. This difference between the 
Oregon form and the California Bleistocene Aretotheriuni is well 
shown in transverse diameter and thickness of the narrowest portion 
of the shaft at the lower end of the pectoral ridge. The supinator 
ridge is strongly developed as in A. simum, and is higher or wider 
than in either the Potter Creek Cave or the Bancho La Brea specimens. 
The flat area between the deltoid and pectoral ridges is more strongly 
marked and wider than in the California Pleistocene Aretotheriuni 
specimens. The lower end of this area also extends relatively 
much nearer the distal end of the shaft than in A. simum, and in side 
view (fig. 15c) is seen to project farther anteriorly. A large ent- 
epicondylar foramen is present as in Arctotherium. The bar of bone 
forming the outer boundary of this foramen is largely broken away, 
but the remaining portion appears relatively heavier than in Arcto- 
tlu num. The upper end of the foramen seems more broadly rounded 
than the superiorly narrowed foramen in A. simum. 

( hi the whole the humerus is of a much more massive type than 
that of the California Arctotherium, and in this respect suggests the 
relatively heavy skeletal elements of Hyaenaretos. 

The proximal half of the right ulna (figs. 16a and lQb) resembles 
in many respects the corresponding element of Arctotherium simum, 
but it is much larger and more massive than the California Pleistocene 
specimens. The anteroposterior diameter or greater width of the 
shaft seems relatively longer in no. 12!23<>12 than in the Arctotherium of 
California, and one might assume that in the Pliocene form this 
element was relatively somewhat stronger and heavier. The olecranon 
region of no. 22.'!(>2 is longer than in A. simum and the anterior 
tuberosity of the olecranon is considerably higher. The posterior 
region of the olecranon is sharply twisted toward the inner side as in 
Ursus and Arctotherium. The anterior tuberosity is separated from 
the twisted posterior angle of the olecranon by a sharply marked 
concave surface which is not represented on the olecranon in Arcto- 
lli< rium and Ursus. The greater sigmoid cavity is deep and the lesser 
sigmoid cavity is distinctly concave. 

in no. 22362 the ulna differs from a specimen described as Hyaen- 
aretos from the Siwaliks of the Saharanpur district by Lydekker. 3 
The Indian specimen was assumed by Lydekker to represent Hyaen- 

3 Lydekker, R., Records, Geol. Survey of India, vol. 21, part 4, p. 143, 1888. 



1916] Merriam-StocJc-Moody : An America)) Pliocene Bear 99 




Figs. 15a to 16&. Indarctosf ? ) oregonensis, n. sp. Humerus and ulna, no. 
22362, X Vi- Fig. 15a, humerus, proximal view; fig. 15&, humerus, anterior 
view; fig. 15c, humerus, inner view. Fig. 16a, ulna, outer view; fig. 16b, ulna, 
anterior view. Rattlesnake formation, John Day Valley, Oregon. 



100 University of California Publications in Geology [Vol. 10 



arctos, although not found with other material representing that 
genus. It shows a somewhat longer olecranon, and a much more 
prominent anterior tuberosity than appears in the Oregon specimen. 
The anterior tuberosity is also nearer the proximal border of the 
greater sigmoid cavity in the Indian form. Lydekker called attention 
to the similarity of the Indian specimen to the ulna of Amphicyon. 

Metacarpal 5 (figs. 17a to 17 d) resembles in general the form of 
this element in the bears, especially that in Arctotherium. The Oregon 
specimen differs greatly in proportions from A. simum and A. cali- 
f ornicum of the California Pleistocene. In no. 22362 this element has 
almost exactly the same length as specimen 30-10 representing A. simum 
from Potter Creek Cave, but is very much thicker and heavier than 
the Potter Creek Cave specimen. The thickness of no. 22362 approxi- 
mates that in the type of A. calif ornicum, from the Pleistocene of 
Rancho La Brea, but the shaft in the Rancho La Brea specimen is 
much longer and more slender. The Oregon specimen differs from 
the known California arctotheres in details of structure of metacarpal 
5 as well as in proportions. In no. 22362 the distal articulation is 
more strongly bulbous on the superior side, and the median inferior 
keel is thicker and decidedly more prominent at the posterior end. 
At the distal end of the superior surface of the shaft there is a marked 
depression immediately posterior to the bulbous distal articulation, 
whereas in the California arctotheres this area may be flat rather than 
concave as in no. 22362. Also at the distal end of the inferior surface 
of the shaft there is a distinct concavity in the Oregon specimen, 
while in A. simum and A. calif ornicum this region tends to be convex. 
In the middle of the superior surface of the shaft no. 22362 is strongly 
convex along the anteroposterior contour, while in the California 
Arctotherium specimens this outline is nearly straight. The proximal 
articular face of no. 22362 is narrower transversely than in either 
A. simum or A. calif ornicum. 

The specimen representing metatarsal 2 (figs. 18a and 18&) is not 
as well preserved as the fifth metacarpal, and less satisfactory material 
of Arctotherium is available for comparison. In this metapodial, as 
in metacarpal 5, the tendency is toward somewhat greater thickness 
than in Arctotherium, but the element does not appear relatively as 
short compared with the corresponding element of Arctotherium as is 
the case in metacarpal 5. At the distal end the keel is^somewhat more 
prominent than that in a specimen of A. simum from Potter Creek 
Cave. 



1916] Merriam-Stock— Moody : An American Pliocene Bear 




Figs. 17a to 21c. Indarctosf ? ) oregonensis, n. sp. No. 22362, X V_>- Fig. 17a, 
metacarpal 5, dorsal view; fig. 17b, metacarpal 5, median view; fig. 17c, meta- 
carpal 5, proximal view; fig. 17&, metacarpal 5, distal view. Fig. 18a, meta- 
tarsal 2, dorsal view; fig. 18b. metatarsal 2, inner view. Fig. 19a, phalanx 1, 
dorsal view; fig. 19b, phalanx 1, ventral view. Fig. 20, navicular, proximal view. 
Fig. 21a, cuboid, dorsal view; fig. 21b, cuboid, median view; fig. 21c, cuboid, 
proximal view. Rattlesnake formation, John Day Valley, Oregon. 



102 



University of California Publications in Geology t VoL - 1(1 



A navicular (fig. 20) of the left foot is somewhat larger than the 
corresponding bone in the specimen of A. simum from Potter Creek 
Cave. The differences in the form of the element are not large. 
Although the navicular in no. 22362 is noticeably broader than the 
corresponding tarsal element in Arctotherium from Potter Creek Cave, 
it lias approximately the same depth. In the Pliocene specimen 
the facet for the astragalus is not as deeply concave as that in Arcto- 
therium. The ventral portion of the articulating surface for the 
cuboid is larger and truncates the lateral margin more acutely than 
in the latter genus. Along the external border of the navicular this 
surface is less extensive than in Ursus. The union of the median 
and ventral borders is less distinctly rounded than in A. simum. The 
distal articulating surface is obscurely divided for the cuneiform 
elements. The ventral tubercle is large. 

The cuboid 'figs. 21a to 21c) possesses a long inner side and 
approaches more nearly a euboidal form than does the corresponding 
element in the Recent Ursus. The cuboid of the Pleistocene Arcto- 
l/n mi in from Potter Creek Cave is in this regard intermediate between 
that of no. 22362 and Ursus. In contrast to Arctotherium the angle 
between the dorsal plane and the plane of the metatarsal facet in the 
Pliocene cuboid is less acute. 

The larger cuboid facet for the navicular is subtriangular. It is 
separated from an inner facet for the astragalus by a right angle, and 
is directed decidedly toward the ventral side. In Arctotherium and in 
Ursus this surface is directed more toward the inner side of the cuboid 
and is separated from the astragalar facet by an obtuse angle. The 
distal end of the boundary between the navicular and astragalar facets 
is truncated by a very small articulating surface also for the navicular, 
The latter has a greater dorso-ventral extent in Arctotherium . 

The concave cuboid facet for the astragalus differs in its greater 
size and rectangular form from that in Arctotherium and in the Recent 
Ursus. Distal to this facet and widely separated from it is a large and 
flat articulating surface for the external cuneiform. In A. simum 
this surface is broadly confluent with the navicular facet. It is situated 
farther to the ventral side in no. 22362 than in the cuboid of A. simum. 
Only a single facet articulates with the external cuneiform at the 
distal margin of the cuboid. 

The metatarsal facet of the cuboid is triangular and relatively 
smaller than in Arctotherium. On the ventral side of the cuboid the 
transverse ridge is situated farther proximally, especially toward the 



1916] 



Merriam-S took— Moody : A n 



American Pliocene Bear 



103 



outer end, and the inner end is not as thick as in Arctotherimn. The 
peroneal groove is much deeper than in either Arctotherium or Ursus, 
indicating a well developed peroneal muscle. 

Two phalanges of the proximal series were recovered. One of 
the specimens (figs. 19a and 196) is much longer than the other. They 
are both much larger than the first phalanges in Ursus and Arcto- 




22b 

Fiys. 22a and 22b. Atlas associated with type specimen of Indarctosf ? ) 
oregonensis. No. 22362?, X %. Fig. 22«, dorsal view; fig'. 22b, posterior view. 
Rattlesnake formation, John Day Valley, Oregon. 

thcriwm simwm under observation. Both are noticeably compressed 
dorso-ventrally, as is the bears. The distal end is flexed downward, 
giving a distinct longitudinal arch to the dorsal surface. The proximal 
extremity is relatively broad and its ventral border is deeply notched. 

An atlas (figs. 22a and 226) found associated with rib fragments 
near the locality of no. 22362 represents a very large carnivore with 



104 University of California Publications in Geology [Vol. 10 



characters differing from those of Arctotherium; the true bears, and 
such other carnivores as would be expected to occur in this formation. 
The atlas is much larger than that of an Arctotherium specimen from 
Potter Creek Cave, and differs from it structurally in several particu- 
lars. The lateral wings are broken, but seem to have been broad and 
to have extended with a wide sweep posteriorly somewhat as in 
Ursus. The posterior portion of the lateral wings extends behind the 
facets for articulation with the axis, as in Smilodon, without an inter- 
ruption or notch such as appears in Arctotherium, Ursus, the dogs, 
and the true cats. In the specimen found near no. 22362 the extension 
of the wings behind the axis facets is buttressed by a high superior 
ridge which runs across the region in which the notch would be sit- 
uated in the true bears or in Arctotherium. In this particular this 
atlas is again similar to that of Smilodon. One of the most important 
characters is found in the position of the vertebrarterial foramen, 
which in the Pliocene specimen is situated low down at the posterior 
border of the lateral wings, and immediately behind the facets for 
the axis. This situation is much as in Smilodon. In Ursus the 
posterior opening of this foramen is situated high up on the posterior 
side of the lateral wings. In Arctotherium it is situated considerably 
in advance of the postero-superior border of the wings. The position 
of this foramen in Arctotherium resembles more closely that of the 
dogs than in the case of Ursus. 

The atlas from the Rattlesnake differs from that of the cats and 
the clogs in that the passage for the vertebral artery through the 
anterior side of the lateral wings is in an enclosed foramen instead 
of in a groove or notch in the anterior border. Tn this respect this 
atlas resembles that of Ursus and Arctotherium. 

The characters of the atlas found near no. 22362 resemble those 
of the bears in the nature of the anterior portion of the vertebrarterial 
passage, resemble the cats in the nature of the posterior extremity of 
this canal, and resemble Smilodon in the form of the posterior border 
of the lateral wings. It is interesting to note that, whereas the atlas 
of Arctotherium is in certain respects more dog-like than that of 
Ursus, the Rattlesnake specimen differs widely from the dogs in the 
particular characters in which Arctotherium approaches them, and in 
these characters the Rattlesnake form resembles Smilodon more closely. 



19H5] Merriam- Stock- Moody : An American Pliocene Bear 



105 



Measurements op Skeletal Parts 

No. 22362 

Humerus — • 

Length from head to radial articulating surface </490 mm. 

Anteroposterior diameter of head al22 

Transverse diameter of head at tuberosities « 108.3 

Anteroposterior diameter of shaft at distal end of deltoid crest.... 81.4 

Least transverse diameter of shaft 53.6 

Width of distal end al58 

Ulna- 
Distance from proximal end of greater sigmoid cavity to end of 

olecranon 80.3 

Greatest anteroposterior diameter at coronoid 98.6 

Greatest transverse diameter of shaft distal to greater sigmoid 

cavity 38.4 

Metacarpal 5 — 

Greatest length 103.6 

Greatest anteroposterior diameter of proximal end 39 

Transverse diameter of proximal end «32.4 

Transverse diameter at middle of shaft 21.5 

Transverse diameter of distal end c/30 

Metatarsal 2 — ■ 

Greatest length 94 

Anteroposterior diameter of proximal end o28.2 

Transverse diameter of proximal end al8.3 

Transverse diameter at middle of shaft 18 

Anteroposterior diameter at middle of shaft 12.8 

" Navicular — 

Greatest width 44.2 

Greatest depth 46 

Cuboid — ■ 

Greatest proximo-distal diameter 40.4 

Greatest transverse width a49.4 

Depth of metatarsal facet 36.8 

Width of metatarsal facet 34.2 

Phalanx 1 — 

Greatest length 61.2 

Width of proximal end 28.8 

a, approximate. 



EELATIONSHIPS 

Although the representation of dentition and skeleton of the 

Oregon Pliocene bear is scanty, the elements available for study are 

f 

fortunately among the most important that could be selected for 
comparative study. In the dentition the second upper molar and the 
upper earnassial have larger significance than all other members of 
the dental series for the particular comparison before us. 

The broader relationships of the Rattlesnake bear are as clearly 
shown by M2 and P± as they could be by M T , while the greater varia- 



106 University of California Publications in Geology [Vol. 10 



bility of these two upper teeth tells the story with more detail and 
gives expression to the closer affinities. The few skeletal elements 
present, though leaving much to be desired, show characters of high 
value in estimating the more intimate relationships of this form. 

The Oregon Pliocene bear approximates the characters of Inclarctos 
salmontanus Pilgrim in the structure of M-, the only available tooth 
representing that genus. The characters seen in the type of Inclarctos 
and in the Oregon specimen are not found in other known forms. 
These characters arc must nearly approached in M- of Hyaenarctos, 
Arctotkerium, and Aeluropus; and are intermediate between those 
of Hyaenarctos and Arct other ium. In the characters of P- the Oregon 
specimen docs not differ essentially from the several known species 
of Hyaenarctos, but is distinctly different from Arct other ium, 
Aeluropus, and all other known forms referred to the bear group. 

If as is indicated by the characters of M- the Oregon form belongs 
to the same general group of bears as Inclarctos salmontanus, and shows 
approximately the same stage of evolution, it seems probable that the 
Siwalik Inclarctos also possessed the Hyaenarctos type of P-. From 
slender evidence furnished by strength of the maxilla and form of a 
small portion of the posterior border of the alveolus of I Ji , Pilgrim 4 
inferred that P- of I. saliimutanus was large and possessed a distinct 
inner root; and that its inner cusp or deuterocone did not occupy 
an extreme posterior position as in Helarctos, in all modern bears, 
and in the Pliocene and Pleistocene types referable to Ursus. With 
such evidence as is at hand it may be assumed that P- of Pilgrim's 
Inclarctos was not materially different from that in the Oregon 
specimen. 

The characters of the massive limb elements of the Oregon speci- 
men, so far as they are known, suggest the limb type of Hyaenarctos, 
and indicate a rather wide separation from Arctotherium. 

The sum of the known characters of the Oregon bear, specimen 
22362, represent a type near Hyaenarctos, but tending toward Arcto- 
therium in the development of its last upper molar. The Oregon 
form cannot be sharply separated from the Siwalik type of Inclarctos 
on the basis of available material. Differences in proportions of the 
tubercles of M2 suggest the specific divergence which is to be expected 
in forms found in regions so widely separated geographically as India 
and Oregon. The Oregon form may be referred tentatively to the 
genus Inclarctos with the specific name oregoneusis. 

i Pilgrim, G. E., Becords, Geol. Surv. India, vol. 44, part 3, p. 230, 1914. 



1916] Merriam-Stock-Moody : An American Pliocene Bear 107 



The Indarctos group is nearer to Hyaenarctos than to Arcto- 
therium, and as suggested by Pilgrim 5 the discovery of a type inter- 
mediate between Hyaenarctos punjabiensis and Indarctos salmontanus 
might make it difficult to establish a generic separation between Ind- 
arctos and Hyaenarctos. 

The occurrence in the Oregon Pliocene of a form closely allied to 
an Indian Siwalik type suggests close faunal relationship of Asia and 
North America in early Pliocene time. The presence of a form of 
the Hyaenarctos type with characters tending toward those of 
Arctotherium in the North American Pliocene also gives support to 
the assumption that the American Arctotherium is derived from a 
line passing near that of Hyaenarctos. It is now possible to consider 
the origin of Arctotherium in America rather than in Eurasia. As 
no bears of the Ursus type are known from the Pliocene of America, 
we may conceive of Arctotherium as originating in North America 
in the Pliocene and entering South America before Ursus was present 
in the New World. This would account for the large Pleistocene 
development of Arctotherium in South America in absence of Ursus. 
though the two groups appear together in the North American 
Pleistocene. 

A large lower carnassial of a bear-like animal (figs. 23a and 235) 
from the brown coal of Tehuichila near the boundary between the states 
of Hidalgo and Vera Cruz, Mexico, was thought by Freudenberg' ; to 
resemble Hyaenarctos. This specimen was found in beds containing 
a Hipparion fauna, and presumed to be of upper Miocene or lower 
Pliocene age. An excellent cast of the Mexican specimen kindly 
furnished by Dr. Freudenberg is available for comparative study. 
This tooth resembles in many respects the lower carnassial of a 
specimen referred to Hyaenarctos punjabiensis by Lydekker. 7 The 
general form of both the trigonid and talonid portions of the tooth 
is like that of Hyaenarctos, and the proportions compared in antero- 
posterior diameter are approximately the same. Unfortunately the 
Mexican specimen is broken in the region of the metaconid, but as 
nearly as can be determined this portion of the tooth may not have 
been widely different from that of the Indian genus. 

The occurrence of the specimen from Tehuichila is presumably 
at a horizon not widely removed from that of the Rattlesnake Pliocene 

s Pilgrim, G. E., op. cit., p. 227, 191 4. 

a Freudenberg, W., Geol. u. Palae., Abb.. N. F., Bd. 9, p. 13, 1910. 
"Lydekker, R., Mem. Geol. Surv. India, ser. 10, vol. 2, pi. 31, fig. 1, 1881. 



108 



University of California Publications in Geology 



[Vol. 10 



of Oregon, and there can be little doubt that, as suggested by Freuden- 
berg, the form represents the general group of Hyaenarctos. The 
closer relationships can hardly be determined with certainty, but it 
is of great interest to note that this group is represented in beds of 
approximately lower Pliocene or late Miocene age in Mexico, adjacent 
to the South American region, in which the arctotheres were so largely 
developed in the Pleistocene. 



Figs. 23a and 23b. Hyaenarctoft or Indarctos. Mj, natural size. Fig. 23a, 
outer view; fig. 23b, occlusal view. From late Cenozoic deposits, Tehuichila, 
Mexico. (Drawn from cast furnished by Dr. W. Freudenberg.) 



Two forms from South America described by Ameghino as Par- 
arctotherium and Proarctotherium have been assumed to be ancestral 
types of the South American arctotheres. Pararctotheriuni is 
known from the Pampean formation, which corresponds to a eonsider- 
able portion of the Pleistocene of North America. Pararctotheriuni 
is clearly a member of the Arctotherium group in which M 5 is con- 
siderably specialized. The anterior premolars of Pararctotheriuni are 
crowded, and the facial region was evidently shortened. There is no 
good reason for considering that this type is ancestral to Arctotherium; 
in fact, it may lie one of the more specialized members of the Arcto- 
tln rium group. 

Proarctotherium is known from a very fragmentary specimen 
consisting of Mj and Mg from Parana, The Parana deposits have 
been assumed to be Pliocene, and may contain a small number of North 
American Pliocene types. Ameghino 's s figure of the type specimen 

8 Ameghino, F., Contribucion al conocimiento de los mamiferos fosiles de la 
Eepublica Argentina, p. 319, pi. 21, fig. 1, 1889. 




23a 



1916] Merriam— Stock-Moody : An American Pliocene Bear 109 



shows a M5 not differing materially from that of Arctotherium. M 5 is 
large and elongate, approximating the form seen in typical Pleistocene 
Arctotherium, as in A. simum. 

The type specimen of Proarctotherium evidently represents a 
typical member of the Arctotherium group. As the occurrence of 
a representative of the Hyaenarctos type seems now fairly established 
for the late Tertiary of Mexico, it is of course possible that a member 
of the group reached South America with the earliest of the Pliocene- 
Pleistocene emigrants from North America. While the characters of 
I? in the Parana form do not differ greatly from those of Hyaenarctos, 
is of a distinctly more advanced type. The nature of the 
specialization of M s is such as we commonly find associated with an 
anteroposterior^ elongated heel of the last upper molar, and is not 
to be expected in a Pliocene bear. Apparently the geologic occurrence 
of the Parana specimen must remain in doubt until other material of 
this nature appears in the Parana. 



Transmitted October 25, 1916. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

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Vol. 10, No. 8, pp. 111-127, 21 text-figures 1 , d Dec ember 23 1916 

Vol. 10, No. 9, pp. 129-135, 3 text-figures / lssuea uecemDer iyi ° 



MAMMALIAN REMAINS FROM THE CHANAC 
FORMATION OF THE TEJON HILLS, 
CALIFORNIA 




MAMMALIAN REMAINS FROM A LATE 
TERTIARY FORMATION AT 
IRONSIDE, OREGON 

BY 

JOHN C. MERRIAM 



UNIVERSITY OF CALIFORNIA PRESS 
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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

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GEOLOGY 

Vol. 10, No. 8, pp. 1 1 1-127, 21 text-figures 



s JAN y- t . 
2j«ai Muse 

Issued December 23, 1916 



MAMMALIAN REMAINS FROM THE CHANAC 
FORMATION OF THE TEJON HILLS, 
CALIFORNIA 

BY 

JOHN C. MEEKIAM 



CONTENTS 

PAGE 



Introduction Ill 

Stratigraphie position of mammal-bearing Chanac formation in the Tejon 

Hills . 112 

Composition and relationships of mammalian fauna of the Chanac formation 116 

Description of Chanac mammalian fauna 117 

Bhinoeerotid and mastodontine remains 117 

Neohipparion gratum tehonense, n. subsp 118 

Neohipparion, near molle Merriam 120 

Limb fragments of Neohipparion 122 

Protohippus tehouensis Merriam 125 

Prosthennops, sp 126 

Camelid, indet 127 

Meryeodus, near neeatus Leidy 127 



INTRODUCTION 

Within a few weeks following the publication of a note 1 on mam- 
malian remains from the Tejon Hills of California, in 1915, a party 
representing the Department of Palaeontology of the University of 
California visited the Tejon Hills, at the request of the writer, to 
secure additional material, and to make further study of the occur- 
rence of the fauna. This party, consisting of J, P. Buwalda, B. L. 
Clark, and F. E. Vanghan, examined the Tejon Hills area in which 
the first material was found and re-studied with care the beds from 



1 Merriam, J. C, Eemains of land mammals from marine Tertiary beds in the 
Tejon Hills, California, Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, pp. 283-288, 
1915. 



112 University of California Publications in Geology [Vol. 10 



which R. W. Pack of the United States Geological Survey, and later 
R. H. Stoner of the University of California, secured the interesting 
mammalian remains described in 1915. 

For important mammalian material secured, and for additional 
data concerning the sequence of formations and occurrence of mam- 
malian remains, the writer is much indebted to the party visiting 
the Tejon Hills area in 1915. Reports on the geologic occurrence 
furnished by members of the 1915 party are given in full in the dis- 
cussion of stratigraphic position following. 

STRATIGRAPHIC POSITION OF MAMMAL-BEARING 
CHANAC FORMATION IN THE TEJON HILLS 

As noted in the earlier publication- on the Tejon Hills fauna, 
difference of opinion has existed concerning the formation sequence 
and the age of the deposits containing mammalian remains obtained 
in this area. The geologic section has not been easily understood, 
and age determination could not readily be made without fuller in- 
formation as to invertebrate faunal sequence of the Pacific Coast 
Province than was at hand at the time of the first examination of the 
Tejon Hills region. In the earlier studies there seemed good reason 
for considering that remains of land mammals were found in strata 
containing a marine invertebrate fauna comparable to that of beds 
of the Temblor Range referred to Lower Miocene. Other opinion sug- 
gested tentatively the "Santa Margarita" or late Miocene age of the 
mammal-bearing formation. 

With the evidence available at the time of publication of the 
earlier paper 3 the writer concluded that intensive study of the in- 
vertebrate fauna of the Tejon Hills would be necessary before a fully 
satisfactory correlation with other marine Tertiary formations of the 
San Joaquin Valley could be made, and expressed the view that 
faunas of both "Santa Margarita" and "Temblor" stages might be 
represented in the section. 

As is stated in the reports by Dr. Buwalda and Dr. Clark given 
below, the work of the 1915 party points toward the existence of three 
divisions or three formations in the geologic section of the Tejon Hills. 
The divisions reported are: (1) marine "Temblor" or Monterey, 
generally considered as Lower Miocene; (2) marine "Santa Mar- 

2 Merriam, J. C, op. (At., 1915. 

s Merriam, J. C, op. ait., pp. 284 and 285, 1915. 



1916] Merriam: Mammalian Remains from the Tejon Hills 113 



garita," considered as Upper Miocene; and (3) an alluvial or fresh- 
water formation described as the "Chanac" by Dr. Buwalda. An 
unconformity is reported to occur between "Temblor" and "Santa 
Margarita." The Chanac formation is later than the "Santa Mar- 
garita" and is presumed to be unconformable upon it, but the evi- 
dence is not complete on this point. 

The 1915 party found remains only in beds of the uppermost or 
Chanac formation, though they occurred at localities in close prox- 
imity to marine beds. 

Following are the statements as to geologic sequence and occur- 
rence of mammalian fauna by Dr. Buwalda and Dr. Clark : 

Note on the Geology of the Tejon Hills, Furnished by J. P. Buwalda 

The Tejon Hills occupy an area about seven miles long in a north- 
south direction and about three miles wide, on the eastern side of the 
southern end of the San Joaquin Valley. They rise to heights of 
six hundred to eight hundred feet above the floor of the valley, and 
present a subdued topography. 

The section in the Tejon Hills contains three Tertiary formations. 
The lowermost is a series of sandstones and conglomerates considered 
by Dr. B. L. Clark to be of Monterey age (Vaqueros or Temblor, 
marine Lower Miocene). Overlying these strata unconformably is 
a formation considered by Dr. Clark to be the equivalent of the ' ' Santa 
Margarita" (marine Upper Miocene). The uppermost formation is a 
terrane which is apparently of terrestrial origin. 

The Monterey is exposed over an area about two and one-half 
miles in length between Comanche Creek and the escarpment of old 
crystalline rocks of the Sierra Nevada. It lies on an eroded surface of 
the crystalline rocks and is not faulted against them. The formation 
consists of dark gray and yellow sandstones. It is often conglomer- 
atic, and is usually rather coarse and massive. Conglomerate beds 
occur especially in the upper and lower parts of the formation. The 
pebbles and boulders are usually quartz and are well waterworn. The 
thickness is estimated at about three hundred feet. The formation dips 
gently toward the west and away from the crystalline rocks. It con- 
tains a marine fauna determined by Dr. B. L. Clark as Lower Miocene. 

In the northern end of the Tejon Hills, strata of distinctly differ- 
ent character overlie the Monterey just described and extend up on 
the crystalline rocks. They are exposed over an irregular area about 
two miles in diameter around the lower portion of Comanche Creek. 
These beds consist of strikingly white and cream-colored quartzose 



114 University of California Publications in Geology [ V ° L - 10 



sandstones and gravels, and clay strata. The sandstones are coarse 
and the grains exhibit markedly the effects of water wear. The con- 
glomerate pebbles and boulders are well rounded and polished. The 
formation has a thickness of perhaps one hundred feet. These beds 
lie with marked unconformity upon the Monterey and contain a 
marine fauna determined by Dr. Clark to be the "Santa Margarita" 
stage of the upper Miocene. At the northern end of the area these 
beds have been more sharply deformed than the Monterey where it 
is known in this area, so that they dip away from the crystalline rocks 
at angles of 25 degrees or more. 

The uppermost stratigraphic member in the Tejon Hills extends 
from the northwest end of the hills over almost the entire remaining 
territory excepting a small area of crystalline rocks exposed at the 
point where Tejon Creek enters the hills, and along Chanae Creek. 
Areally this uppermost member is the most important terrane of the 
Tejon Hills.- In view of their distinctiveness in lithologic character 
and in mode of origin the name Chanae formation is proposed for these 
strata. Lithologieally this formation consists of angular sands and 
coarser angular materials. The particles are mainly rhyolitic and 
display white, yellow and striking reddish-brown colors in exposures. 
The materials are not well classified as to size and are not sharply 
bedded. Their characters are altogether those of a terrestrial deposit 
of the alluvial fan type, and they should be termed fanglomerates. 
Their thickness is estimated to be four hundred to six hundred feet. 
The Chanae fanglomerates rest upon both of the older Tertiary 
formations and in the southern part of the Tejon Hills upon the old 
crystalline rocks. From the geologic evidence it seems probable that 
they bear an unconformable relation to the beds they overlie, but the 
evidence does not appear conclusive. The distinctly different char- 
acter of the materials and of the faunas of the Chanae contrasted with 
the underlying formations, indicates a change from marine conditions 
to the terrestrial conditions, and favors the view of unconformity. 
Theoretically, such changes might be the result of the filling of a 
marine basin and the deposition, without interruption, of terrestrial 
beds upon the marine strata. The areal relations, however, suggest 
unconformity, although no discordance was observed in the attitude of 
the strata of the Chanae and "Santa Margarita," and no pre-Chanac 
surface of erosion. 



1916] 



Merriam: 



Mammalian Remains from the Tejon Hills 



115 



Note on the Marine Tertiary Faunas op the Tejon Hills Section, Furnished 

by B. L. Clark 

Marine deposits of the two stages of the Miocene are represented 
in the Tejon Hills. A number of characteristic species of that phase 
of the Miocene generally known as the Monterey of the local phase 
designated as Vaqueros or Temblor are represented in gray and 
brown sandstone, having a thickness of about 300 feet. These beds 
rest unconformably upon the granite and have a dip of from 10 de- 
grees to 15 degrees. Certain of the species found in this formation 
are generally considered characteristic fossils of the Monterey group. 
Among these forms may be listed the following : 



Seutella andersoni Twitehell 
Seutella merriami Anderson 
Peeten andersoni Arnold 
Leda ochsneri Anderson and Martin 
Oliva californiea Anderson 



Troplion kernensis Anderson 
Conus oweniana Anderson 
Terebra eooperi Anderson 
Turritella oeoyana Conrad 



Disconformably overlying the Vacpieros or Temblor of the Tejon 
Hills is the Santa Margarita Upper Miocene. The beds of this forma- 
tion are best exposed near the mouth of Comanche Creek. Here they 
have a thickness of between 50 and 100 feet. They are generally com- 
posed of light-colored arkose sandstones with which occur lenses of 
clay and gravel. The fauna found in these beds apparently belongs 
to the Astrodapsis whitneyi zone as recognized in the San Pablo group 
of the Mount Diablo region, and to the same horizon as the Santa 
Margarita beds to the north of Coalinga. The following species were 
collected from the Santa Margarita of the Tejon Hills on the west 
side of Comanche Creek near the western boundary of the NW 14, 
sec. 13, T 32 S, R 29 E, M. D. B. and M. 



Dosinia arnoldi Clark 
Metis alta (Conrad) 
Ostrea titan Conrad 
Ostrea, ef. vespertina Conrad 
Peeten crassicardo Conrad 
Peeten crassicardo, n. var. 
Peeten hastatus Sowerby 
Peeten raymondi Clark 
Phaeoides riehthof'eni (Gabb) 
Phacoides sanetaecrucis Arnold 
Pinna alamedensis Yates 



Piteria stalderi Clark 

Saxidomus nuttali Conrad 

Siliqua, cf. lucida (Conrad) 

Venus pertenuis Gabb 

Bulla, sp. 

Oalyptraea, sp. 

Conus, sp. 

Fusinus, n. sp. 

Nassa pabloensis Clark 

Natica, sp. 

Shark teeth 



116 University of California Publications in Geology [Vol.10 



COMPOSITION AND RELATIONSHIPS OF MAMMALIAN 
FAUNA OF THE CHANAC FORMATION 

The representation of mammalian forms obtained in the land- 
laid beds of the Chanac formation is very scanty, but it includes more 
and better preserved material than that upon which the first note was 
based. Following' is a list of the forms now available : 



Bhinocerotid, indet. 
Protohippus tehonensis Merriam. 
Neohipparion gratum tehonense 
Merriam 

Neohipparion, near molle Merriam. 



Prosthermops, sp. 
Camelid, indet. large. 
Meryeodus, near neeatus Leidy. 
Proboscidean (Tetrabelodonf), indet. 



The general aspect of the small assemblage of forms now known 
is not materially different from that originally suggested. It is clear, 
however, that the most commonly encountered horses of this fauna 
represent the genus Hipparion. The best-known teeth are those of 
two small forms, Neohipparion gratum tehonense, closely resembling 
Neohipparion gratum of the Great Plains region; and a form closely 
approaching Neohipparion molle found in the lower portion of the 
Jacalitos-Etchegoin Pliocene section of the North Coalinga region. 
Horses closely resembling those of the Tejon Hills region have been 
found by R. W. Pack in late Tertiary beds on the eastern flank of 
the Mount Diablo Range, southwest of Modesto. Of the Hipparion- 
like horses known in the faunas of the Mohave Desert region, the type 
most closely approaching the Tejon Hills form is found in an unde- 
scribed species obtained in the upper portion of the Ricardo Pliocene 
section. The Ricardo form does not, however, seem to be specifically 
identical with that from the Tejon Hills. The Tejon Hills horse 
described as Protohippus tehonensis has some resemblance to a form 
found in the upper Miocene Barstow formation of the Mohave Desert, 
but seems not to be specifically identical with the Barstow form. The 
Tejon Hills Protohippus also shows similarity to a species known in 
the lower portion of the Jacalitos-Etchegoin section of the North 
Coalinga region. 

The rhinocerotid and mastodontine remains from the Tejon Hills 
furnish no definite evidence as to age. Rhinoceroses are well repre- 
sented in the Thousand Creek and Rattlesnake Pliocene of Nevada 
and Oregon, and are known in the Pliocene of the Pinole Tuff type 
section in San Francisco Bay region of California. It is interesting 
to note that as yet no remains of rhinoceroses have been secured from 



1916] Merriam: Mammalian Remains from the Tejon Hills 117 



any of the four Cenozoic faunas of the Mohave Desert. It is pos- 
sible that they are present in both the Barstow and Ricardo, but 
have not been recognized. Abundant material is, however, available 
from both Barstow and Ricardo with no recognized remains of 
rhinoceroses, while both of the exceedingly scanty collections from the 
Tejon Hills have included fragments of rhinoceros teeth. The 
rhinoceros group possibly avoided the peculiar habitat of the Mohave 
Desert, and may have existed in the California province west of the 
main divide during the period in which Miocene and Pliocene forma- 
tions were being deposited in the Mohave area. 

The Merycodus and camel remains of the Chanac fauna are not 
sufficiently characteristic to give us a determination of the rela- 
tionship of the Tejon Hills assemblage to that of the Barstow and 
Ricardo. The single Merycodus tooth is very close in its form and 
dimensions to teeth from the Ricardo, and may represent the same 
species. The Merycodus horn fragments are not to be distinguished 
from types represented in both the Barstow and Ricardo faunas. 

The available evidence furnished by the Chanac mammalian fauna 
indicates that it represents a stage older than the Pliohippus pro- 
versus zone of the Upper Etchegoin in the North Coalinga region, and 
later than the Barstow, the youngest recognized Upper Miocene of 
the Pacific Coast and the Great Basin provinces. The Chanac is evi- 
dently of an early Pliocene or latest Miocene phase. It is presumably 
nearest to the faunas of the lower portion of the Jacalitos-Etchegoin 
of the North Coalinga region and to the Ricardo stage of the Mohave 
area. 

DESCRIPTION OP CHANAC MAMMALIAN FAUNA 

EHINOCEROTID AND MASTODONTINE EEMAINS 

In the earlier discussion of the Tejon Hills fauna a fragment of a 
large tooth, 4 at first assumed to represent a proboscidean, was tenta- 
tively considered as a member of the Rhinocerotidae, as the structure 
of the outer wall closely resembled that of rhinoceros tooth forms. 
In the collection obtained in 1915 a portion of a large rhinoceros 
lower cheek-tooth furnishes satisfactory evidence of the presence of 
this group in the Chanac fauna. This tooth fragment, no. 22368, 
represents a large animal of uncertain systematic position. The pres- 
ence of a rhinoceros in the Tejon Hills fauna is a matter of consider- 

* Merriam, J. C, op. cit., fig. 6, 1915. 



118 University of California Publications in Geology [Vol. 10 



able interest, as no remains representing the Rhinocerotidae have been 
recognized in either the Barstow or the Ricardo fauna. A calcaneum 
representing a member of this group is known in the fauna of the 
Pinole Tuff Pliocene of middle California, and the group has been 
reported from the Thousand Creek and Rattlesnake Pliocene of north- 
ern Nevada and Oregon. It is possible that in late Tertiary time this 
group did not range into the Mohave Desert area. 

NEOHIPPARION GRATUM TEHONENSE, n. subsp. 

Type specimen, no. 21780, from the Chanac formation of the Tejon Hills at 
the southern end of the San Joaquin Valley, California. 

This species corresponds approximately in size and form to Neo- 
hipparion gratum of the Great Plains region. It is doubtfully dis- 
tinguished from the typical form of that species by the tendency to 
show a more nearly circular cross-section of the protocone and by 
somewhat dubious characters in width of crown and nature of the 
enamel folds bordering the fossettes. 

The character of the protocone of the Chanac form (figs, la to lc) 
suggests Hipparion plicatile of the Alachua clays of Florida, but the 
crowns in that species seem larger and relatively wider than in the 
Chanac species. H. ingenuum also of the Alachua clays is not widely 
removed from the Chanac species, but the protocone is smaller. The 
Chanac species differs from Neohipparion montezumae in its more 
nearly circular section of protocone and possibly in a tendency to rela- 
tively greater transverse diameter of the fossettes. 

The characters of the Chanac species represented by specimen 
21780 are in general like those of Hipparion, mohavense of the Ricardo 
Pliocene, but they are shown in a form with smaller dimensions, and 
approaching the combination of characters of N. gratum. The species 
is evidently very near the Great Plains form of N. gratum, and it is 
not impossible that larger collections will exhibit a range of characters 
making even subspecific separation inadvisable. 

An upper molar (figs. 8a to 8c) obtained by R. W. Pack of the 
United States Geological Survey on the north side of Hospital Creek 
(SE corner sec. 11, T 4 S, R 5 E) is similar to N. g. tehonense in 
dimensions. In this specimen the protocone is very small and approx- 
imately circular in cross-section. 

An upper cheek-tooth figured in the earlier paper on the Tejon 
Hills fauna 5 may represent N. g. tehonense, or is possibly a more 
primitive form. 

3 Merriam, J. C, op. cit., p. 286, fig. 1, 1915. 



1916] Merriam: Mammalian Remains from the Tejon Hills 119 




Fig. 1. Neohipparion gratum tehonense Merriam. M 1 ?, type specimen, no. 
21780, natural size. Fig', la, occlusal view; fig. lb, outer view; lig. lc, posterior 
view. Chanae formation, southern end of San Joaquin Valley, California. 

Fig. 2. Neohipparion gratum tehonense Merriam. P±, no. 21782, natural 
size. Chanae formation, southern end of San Joaquin Valley, California. 

Fig. 3. Neohipparion, near molle Merriam. M-, no. 21781, natural size. 
Chanae formation, southern end of San Joaquin Valley, California. 

Fig. 4. Neohipparion gratum tehonense Merriam. Pj, no. 21784, natural size. 
Chanae formation, southern end of San Joaquin Valley, California. 

Fig. 5. Neohipparion gratum tehonense Merriam. Mj, no. 21785, natural 
size. Chanae formation, southern end of San Joaquin Valley, California. 

Fig. (J. Neohipparion, near gratum tehonense Merriam. M^?, no. 22364, 
natural size. Chanae formation, southern end of San Joaquin Valley, California. 

Fig. 7. Neohipparion, near gratum tehonense Merriam. Mj, no. 21786, 
natural size. Chanae formation, southern end of San Joaquin Valley, California. 



120 



University of California Publications in Geology [Vol. 10 



A single fragmentary upper cheek-tooth (no. 1323) from beds pre- 
sumed to belong to the Orinda Pliocene near Bolinger Canyon, Cali- 
fornia, shows the approximate form and dimensions of upper cheek- 
tooth of N. g. tehonense from the Tejon Hills. This specimen has been 
referred to as representing a Hipparion-like type distinct from two 
larger forms known from the Orinda." It is possible that specimen 
1323 represents a species in or near N. g. tehonense. 

Several lower cheek-teeth from the Chanac formation of the Tejon 
Hills represent small Hipparion forms. It is possible that more than 
one species is present. If so the larger teeth as no. 21784 and 21785 
(figs. 4 and 5) presumably represent N. g. tehonense, and the smaller 
specimens, as no. 22364 (fig. 6), might belong with the narrower 
upper cheek-teeth approaching Neohipparion niolle. The small lower 
cheek-teeth from the Chanac formation approach the characters of a 
small Hipparion specimen (no. 22387) from the Ricardo beds above 
the uppermost basalt in the type section. 

A lower cheek-tooth figured in the first discussion of the Tejon 
Hills fauna 7 corresponds to the smaller of these two faunas. 

NEOHIPPARION, near MOLLE Merriam 
A second upper molar, no. 21781 (fig. 3) from the Tejon Hills 
shows a much narrower crown, narrower fossettes and a flatter proto- 
cone than the specimen distinguished as Neohipparion gratum tehon- 
ense. In width of crown and narrowness of fossettes this specimen 
approaches Neohipparion ) nolle" of the North Coalinga Jaealitos- 
Etchegoin section, but the protoeone is narrower anteroposteriorly. 
In character of protoeone no. 21781 is intermediate between N. molle 
and N. g. tehonense. 

A 1VP (figs. 9a and 9b) evidently representing Neohipparion molle, 
obtained by R. W. Pack of the Geological Survey from beds overlying 
strata referred to the San Pablo, one mile north of Ingram Creek, on 
the east flank of the foothills of the Mount Diablo Range, shows the 
protoeone a little narrower anteroposteriorly than in the type of N. 
■molle. As the type of N. molle and the specimen found by Mr. Pack 
both represent 1VP, it is possible that since the Tejon Hills specimen 
no. 21781 is a M 2 it may also belong in N. niolle, as the protoeone of 
M- is commonly shorter anteroposteriorly than in M^. 

« Merriam, J. C, Univ. Calif. Publ., Bull. Dept. Geol., vol. 7, p. 37(1, fig-. 2, 1913. 
- Merriam, J. 0., Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, p. 286. 
s See Merriam, J. C, Univ. Calif. Publ., Bull. Dept. Geol., vol. 9, p. 3 and 
fig. 2, 1915. 



1916] Merriam: Mammalian Remains from the Tejon Hills 



121 



A M- (figs. 8a to 8c) obtained by Mr. Pack from beds overlying 
strata referred to San Pablo on the north side of Hospital Creek in 
the foothills of the Mount Diablo Range southwest of Modesto shows 
much the same width of crown and narrowness of fossettes as in M- 
obtained by Mr. Pack at Ingram Creek several miles to the southeast, 



Figs. 8«, 8b, and 8c, Neohipparion, near gratum tehonense Merriam. M-, 
natural size. Outer and occlusal views, and section at s near proximal end of 
distal third. Fig. 8a outer view; 8&, cross-section at s; fig. 8c, occlusal view of 
slightly worn tooth. Collected by E. W. Pack, of U. S. Geol. Survey, north side 
of Hospital Creek, western border of San Joaquin Valley, California, at S.E. cor- 
ner sec. 11, T 4 S, E 5 E, M. D. B. & M. 

Figs. 9a and 9b. Neohipparion, near molle Merriam. M 3 , natural size. Fig. 
9a, inner view; 9ft, section at s near proximal end of distal third. Collected 
by E. W. Pack, of U. S. Geol. Survey, one mile north of Ingram Creek, western 
border of San Joaquin Valley, California. 

but the protocone is small and almost circular in cross-section. If 
this specimen by any chance is shown to represent the same form as 
the M^ from Ingram Creek there might be reason for considering the 
possible identity of N. molle and the N. gratum group. For the pres- 
ent there seems good reason for keeping the forms with wide proto- 
cone separate from the group with narrow protocone. 




8a 



9a 



122 University of California Publications in Geology [Vol. 10 

Measurements 

No. 21780 

M 1 ?, anteroposterior diameter 19.1 mm. 

M 1 ?, transverse diameter 17.7 

M 1 ?, anteroposterior diameter of protoeone 6.4 

No. 21781 

M-, anteroposterior diameter 17.8 mm. 

M-, transverse diameter at middle height of crown al6.5 

M=, anteroposterior diameter of protoeone 6.1 

No. 21782 

P 1 , anteroposterior diameter 18.8 mm. 

P 1 , transverse diameter 18.0 

I' 1 , anteroposterior diameter of protoeone 6.6 

No. 21784 

Pj, anteroposterior diameter 20.3 mm. 

Pi, transverse diameter all.l 

P-„ anteroposterior diameter of metaconid-metastylid column 12.9 

No. 21785 

M.r 2 , anteroposterior diameter 19.3 mm. 

Mj, transverse diameter 9.5 

Mi, anteroposterior diameter of metaconid-metastylid column 11.3 

a, approximate. 



LIMB FEAGMENTS OF NEOHIPPAEION 

Two fragments of small metapodials represent an eqnid form not 
larger than the smallest species of Merychippus of the Barstow Mio- 
cene. Specimen 22365 (fig. 10), the proximal end of a small slender 
metacarpal three, possesses a narrow shaft suggesting that of the 
small Barstow Merychippus. The position of the unciform facet is, 
however, quite different from that in all of the many Barstow speci- 
mens examined by the writer. In the Barstow forms the unciform 
facet cuts that of the magnum at an angle ranging betwen 112 and 
121.5 degrees. In the Ricardo horses, so far as known, the correspond- 
ing angle ranges between 128 and 131 degrees, and the unciform facet 
approaches distinctly nearer to the plane of the magnum facet than 
in the Barstow forms. In no. 22365 from the Tejon Hills the magnum- 
unciform angle is 131 degrees, as in the Ricardo horses. 

A second metapodial specimen, no. 22376 (fig. 11) represents 
the distal end of a small metapodial of approximately the size shown 
in no. 22365. In this specimen the median keel is strongly developed 
on the posterior side but, as in the small Barstow Merychippus, it 
tends to fade out in the proximal region of the anterior side. In the 
Ricardo horses the keel is more strongly expressed. 

In a fragmentary specimen representing a proximal phalanx, no. 
22375 (fig. 13) the groove for reception of the distal keel of the meta- 



1916] Merriam: Mammalian Remains from the Tejon Hills 



123 



podial is well marked at the anterior side, showing that the metapodial 
keel was well expressed as in the Hippario n type. The phalanx rep- 
resents an animal of somewhat larger size than the individuals from 
which the small metapodial specimens have been derived. 

A small cuboid, no. 21787 (fig. 12), from locality 2751, has approx- 
imately the size of the corresponding element in small Merychippus 




10 

Fig. 10. Neohipparion, sp. Proximal end of metacarpal 3, natural size, 
anterior anil proximal views, no. 22365. Chanae formation, southern end of 
San Joaquin Valley, California. 

Fig. 11. Neohipparion, or Merychippus. Distal end of metapodial, no. 22376, 
natural size. Chanae formation, southern end of San Joaquin Valley, California. 

Fig. 12. Neohipparion or Merychippus. Cuboid, no. 21787, proximal and 
inner view, natural size. Chanae formation, southern end of San Joaquin Valley, 
California. 

Fig. 13. Neohipparion or Merychippus. Proximal end of first phalanx, no. 
22375, natural size. Chanae formation, southern end of San Joaquin Valley, 
California. 



124 University of California Publications in Geology [Vol. 10 



specimens from the Barstow Miocene. It differs from Barstow speci- 
mens in its slightly less prominent tuberosity, and in the situation of 
the posterior facet for the navicular somewhat nearer the proximal 
end of the element. In these particulars the Tejon Hills specimen 
approaches more closely the characters of an equid cuboid from the 
Ricardo Pliocene. 

At locality 2751, in which the small equid metapodials, the 
phalanx, and the cuboid were found, no Merychippus teeth are known, 




but a number of Neohipparion teeth occurring there show dimensions 
not greater than those of the smallest Merychippus forms of the Bar- 
stow. It is therefore possible that the Merychippus-like limb elements 
represent the little Neohipparion species, in which resemblance to 
Merychippus is especially strong because small size has made unneces- 
sary certain peculiar specializations in structure found in the larger 
and perhaps more nearly typical species of the genus. . 



1916] Merriam: Mammalian Remains from the Tejon Hills 



125 



PROTOHIPPUS TEHONENSIS Merriam 



P. tehonensis Merriam, Univ. Calif. Publ. Bull. Dept. Geol., vol. 9, p. 52, figs. 
4a and 4i) and 4c, 1915. 

This species is represented by a single upper molar, no. 21779, the 
type specimen of the species (figs. 14a to 14c), found at locality 
2751 in the Chanac formation of the Tejon Hills at the southern end 
of the Great Valley of California. 

The West- American types to which Protohippus tehonensis shows 
closest resemblances are a form referred to Pliohippus or Protohippus 
from the lower portion of the Jacalitos-Etche- 
goin section of the North Coalinga" region, and 
a species near Protohippus represented by speci- 
men 21423 from the Barstow Upper Miocene of 
the Mohave Desert. No teeth from the North 
Coalinga form have yet been obtained which 
correspond in position in the jaw to the type of 
P. tehonensis, so that a close comparison is not 
possible. The Barstow species is near the Tejon 
Hills form in many respects, but seems speci- 
fically distinct. 

A lower cheek-tooth, no. 21484 (fig. 15) col- 
lected at Comanche Creek in the Tejon Hills by 
R. C. Stoner has a short metaconid-metastylid 

Fig. 15. — Protohippus column with the valleys anterior and posterior 
or Merychippus. Pr"?, , ,, . , . — . 

outer and occlusal views to this column narrower than m Barstow Mio- 

no. 21484, natural size. eene species which have been considered as very 
Chanac formation, Com- 
anche Creek, southern advanced Merychippus. In the first discussion 

Valley, Calif omfa° aqUin of the Te j° n Hills faunal ° the writer assumed 
that the species represented by this tooth might 
be more progressive than the most advanced Barstow form, and spe- 
cifically distinct from it. This tooth may represent a Protohippus 
differing from the Barstow Miocene forms to much the same degree 
as the upper cheek-tooth in the type of Protohippus tehonensis differs 
from them. It is possible that the specimen represents P. tehonensis. 
The proof of this will require more and better material than that now 
available. 




11 See Merriam, J. C, Tertiary Vertebrate Faunas of the North Coalinga 
Region, Trans. Amer. Phil. Soc. N.S., vol. 22, part 3, p. 27, figs. 28a and 286, 1915. 
io Merriam, J. C, Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, p. 287, 1915. 



126 



University of California Publications in Geology [Vol. 10 



PROSTHENNOPS, sp. 
A number of fragments (no. 22459) from the Chanac formation 
represent a large peccary in which the cusps of the cheek-teeth are 
low or blunt-conical as in Prosthennops. This species approaches cer- 
tain of the imperfectly known peccary forms from Pliocene faunas of 
the Pacific Coast and Great Basin regions. The material available 




Figs. 16 to 21. Merycodus near necatus Leidy. All figures natural size. 
Chanac formation, southern end of San Joaquin Valley, California. Specimens 
represented in figs. 19 and 20 collected by E. W. Pack of U. S. Geol. Survey. 

Fig. 16. or M'j, occlusal and outer views, no. 22366 ; fig. 17, flattened 

superior portion of beam, no. 22332; fig. 18, terminal portion of horn, no. 22367; 
fig. 19, distal end of metatarsus, anterior side ; fig. 20, proximal phalanx, lateral 
and superior views; fig. 21, second phalanx, lateral and superior views, no. 22460. 



1916] 



Merriam: Mammalian Remains from the Tejon Hills 



127 



from the Tejon Hills is too fragmentary, and the characters of the 
western Pliocene species are as yet too imperfectly known to permit a 
satisfactory comparison. 

CAMELID, indet. 

A fragment of the distal end of a large metapodial (no. 22377) 
from locality 2751 represents a camelid possibly of the Pliauchenia 
type. Other very fragmentary material also indicates the presence of 
large camels, but the material available is not sufficient to furnish the 
basis for even a generic determination. 

MEBYCODUS, near NECATUS Leidy 
Fragmentary material obtained in the Tejon Hills region by R. W. 
Pack has already made possible definite determination of the presence 
of Merycodus in this region. Additional specimens secured by the 
1915 party include a fragment of a lower jaw, a lower tooth, a num- 
ber of fragmentary horn-cores, a scapula, and a second phalanx. One 
horn-core specimen (no. 22332, fig. 17) resembles the type of Mery- 
codus found in the Ricardo and Barstow faunas of the Mohave Desert, 
and referred to M. necatus. Other portions of horn-cores, in which 
the cross-section is nearly circular, suggests M. furcatus. The second 
phalanx agrees approximately in size of corresponding parts with 
the first phalanx described in the earlier paper. The single lower 
tooth (no. 22366, fig. 16) is similar to or M T of a small species of 
Merycodus from the Ricardo. On the basis of the Merycodus material 
it is difficult to make a definite estimate of the age of the Chanac 
fauna, but the Tejon Hills form might well represent a stage near 
that of the Ricardo Pliocene. 

Transmitted December 12, 1916. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 9, pp. 129-135, 3 text-figures Issued December 23, 1916 



MAMMALIAN REMAINS FROM A LATE 
TERTIARY FORMATION AT 
IRONSIDE, OREGON 

BY 

JOHN C. MEEKIAM 



INTRODUCTION 

In December, 1915, Dr. W. D. Matthew of the American Museum 
of Natural History kindly called the attention of the writer to a 
reported occurrence of fossil mammalian remains at a locality near 
Ironside. Malheur County, Oregon, the information having come to 
Dr. Matthew through Mr. H. E. Anthony, of the Department of Mam- 
malogy and Ornithology in the American Museum. In subsequent 
correspondence Mr. Anthony informed the writer that a number of 
specimens had been obtained by his father, A. W. Anthony, at various 
localities in Malheur County, Oregon. In later correspondence, Mr. 
A. W. Anthony kindly furnished to the writer such information 
regarding the localities as was available. These discoveries suggested 
the occurrence of a fauna of importance in consideration of the history 
of mammals in the northern portion of the Great Basin province, and 
the writer accepted the invitation of Mr. Anthony to visit the Iron- 
side region and examine the fossil-bearing formation. 

In company with Dr. J. P. Buwalda of the University of California 
the writer had the opportunity to make a hurried survey of this region 
in June, 1916. The writer desires to express his appreciation of the 
courtesies extended by Mr. and Mrs. Anthony during the visit to 
Ironside, and for several interesting mammal specimens presented to 
the University by Mr. Anthony. It is also a pleasure to acknowledge 
the courtesy of Dr. Matthew and Mr. H. E. Anthony in furnishing 
the original information leading to investigations of this locality. 



130 University of California Publications in Geology [Vol. 10 



OCCUBRENCE AND AGE 

The Ironside region, in which the mammalian finds are reported, 
is situated on the extreme northern border of Malheur County, Oregon, 
and is about thirty miles west of the middle of the eastern border of 
the state. This region lies at the southeastern base of the Blue Moun- 
tains, and is at the northern end of the great series of broken plains 
and short mountain ranges extending through southeastern Oregon 
into Nevada. The Ironside region is drained by AA 7 illow Creek, a 
tributary of Malheur River. 

The beds in which the fossil remains were found by Mr. Anthony 
are in the immediate vicinity of Ironside Post Office. Some of the 
exposures are at an elevation of 3800 feet above sea-level. Somewhat 
to the east of Ironside similar sedimentary formations seem to be 
situated at an elevation of at least 4000 feet. 

The mammal- bearing formation consists of buff sandy shales and 
shales with but little sand. The beds stand at varying angles ranging 
up to a degree of inclination of at least 20 degrees. 

Locality 3037. at which the most important specimens were found, 
is located about three-fourths of a mile southwest of Ironside Post 
Office. At this locality, Mr. Anthony secured several fragments of 
upper teeth of Hipparion, a well-preserved lower tooth constituting 
the type of Hipparion anthonyi, a fragment of a rhinoceros tooth, and 
fragments of mastodontine teeth. One quarter of a mile south of 
locality 3037 Elmer Molthan obtained a well-preserved tooth of a 
mastodontine form apparently derived from beds not widely different 
in age from those at locality 3037. 

The equid remains found in the sediments near Ironside represent 
a form most closely approaching in stage of evolution the Hipparion 
species from the Ricardo Pliocene. The stage of evolution of the 
fragmentary equid remains from Ironside is approximately that of 
the Hipparion species known from formations of the Great Basin and 
Pacific Coast provinces generally referred to the Pliocene. There is 
good reason for believing that the sediments at Ironside are not 
younger than middle Pliocene and not older than late Miocene. Future 
investigations should bring out more exactly the age relation of this 
formation to the Rattlesnake Pliocene of the John Day Valley. The 
fauna listed from the Idaho formation by Lindgren 1 in his important 
papers on the Tertiary formations of southwestern Idaho contains as 
one of its important elements equid forms which have been referred 
i Lindgren, W., 20th Ann. Rep. U. S. Geol. Surv., Part 3, p. 99, 1900. 



1910] Merriam: Mammalian Remains from Ironside, Oregon 131 



to Equus, and there can be no doubt that the fauna at Ironside is not 
contemporaneous with that portion of the Idaho formation from which 
Lindgren's Idaho fauna was obtained. 

At the present time some of the important problems in Tertiary 
geology and palaeontology of the Great Basin region depend upon an 
understanding of relationships between the John Day section and that 
of the Idaho region. By reason of its geographic situation the occur- 
rence of mammal remains at Ironside may ultimately be of large 
service in the work of determining the time-relations between the 
Idaho sequence of faunas and the sequence of the John Day region. 
The Ironside locality is so situated that mapping of the region will 
make possible a determination of the stratigraphie relations of the 
sediments to the formations of the Snake River region of Idaho. Large 
exposures of sedimentary formations extend with few apparent inter- 
ruptions from Ironside along Willow Creek and Malheur River to the 
type areas of the Idaho and Payette formations of the Snake River 
Valley. Some of these exposures presumably represent the Idaho 
formation, but it is not improbable that several formations or several 
stages of the later Tertiary are represented. The Ironside locality is 
also situated near the John Day Valley, in which there is represented 
the best stratigraphie section and the best palaeontologic sequence 
known as yet in the Great Basin province. It is probable that further 
palaeontologic and geologic studies will make it possible for us to 
understand the relation between the beds at Ironside and the John 
Day section. There is further the possibility that we may be able to 
determine the relation of the formation at Ironside to a great series 
of Tertiary deposits on the south side of the Blue Mountains, immedi- 
ately to the south of the John Day Valley. The exposures on the 
south side of the Blue Mountains presumably represent a large part 
of the sequence of formations and faunas known within the John 
Day Valley. 

HIPPARION ANTHONYI, n.sp. 

Type specimen a second lower premolar, no. 22351, from Tertiary beds 
exposed three-fourths of a mile south of Ironside, Malheur County, Oregon. 

The species is represented by a single tooth presented by A. W. Anthony of 
Ironside, Oregon. The horizon at which this specimen was found is presumed 
to be early Pliocene or latest Miocene. 

Crown of medium height, narrow transversely. Enamel pattern showing 
uncommonly strong secondary plications. Several very strong secondary 
plications forming a sheaf of projecting folds on anterior side of hypoeonid. 

Specimen 22351 (figs, la to lc) differs from Merychippus and 
PUohippus in its greater relative size and stage of advance of the 



132 



University of California Publications in Geology [Vol. 10 



metaconid-metastylid column and entoconid, and in greater complica- 
tion of its enamel folds. Of the Great Basin and Pacific Coast province 
equids Hipparion mohavense callodonte of the Ricardo Pliocene most 
nearly approaches the form from Ironside. In the West Coast Mery- 



Figs. la to l' 1 . Hipparion cmthonyi Merriam. P;, type specimen, no. 22351, 
natural size. Fig. la, occlusal view; fig. lb, outer view; fig. lc, inner view. 
From late Tertiary beds near Ironside, Oregon. 

Fig. 2. Hipparion anthonyi Merriam?. Fragment of an upper cheek-tooth, 
no. 22355, natural size. From late Tertiary beds near Ironside, Oregon. 

chippus and Pliohippus species the metaconid-metastylid column is 
relatively shorter anteroposterior^, and wider transversely, and the 
entoconid is not filled out to the same extent on the antero-internal 
angle. In general the entoconid of Meryeh ippus and Pliohippus 
species is truncated obliquely on the antero-internal angle by a plane 
or curved face, extending outward and forward from the inner side, 
while in Hipparion this region is expanded and the cross-section of 
the entoconid tends to take on a rectangular outline, instead of the 
approximately triangular section seen in M cry chippus, or the tri- 
angular to imperfectly rectangular but anteroposteriorly short section 
seen in Pliohippus. 

In no Great Basin or Pacific Coast species of Mcrychippus, Proto- 
liippus, or Pliohippus known to the writer does the enamel show such 
a high degree of secondary folding as in the specimen 22351 from Iron- 
side. In Hipparion mohavense callodonte the enamel folds show much 
secondary crinkling, though less than in the Ironside form. The crown 
of H. in. callodonte is slightly larger and relatively thicker trans- 
versely, and the entoconid fuller on the antero-internal angle. In the 




16 



lc 



2 



1916] Merriam: Mammalian Remains from Ironside, Oregon 133 

type specimen of H. m. callodonte there are two small folds on the 
antero-external side of the hypoconid, but these folds are smaller than 
those in this position on the type of H. anthonyi. In other specimens 
from the Ricardo beds the structure differs more from that of no. 
22351 than in the case of the type specimen of H. m. callodonte. 

Of the Hipparion species from the northern end of the Great Basin, 
N eohipparion leptodc of the Thousand Creek Pliocene shows a single 
very strong fold on the anterior side of the hypoconid, but the enamel 
is otherwise comparatively simple and the tooth crown in the type 
specimen, a second lower molar, is extremely narrow. No specimen 
of of N. leptode is known. Prom the Rattlesnake Pliocene of the 
John Day region a specimen with a tooth crown of exactly the same 
height as the type specimen of H. anthonyi shows the enamel very 
much simpler and the crown relatively very much thicker trans- 
versely. Po of Hipparion condoni from the Ellensburg formation is 
unknown. The enamel pattern in //. condoni is fairly complicated, 
but there is much less crinkling in long teeth than in the relatively short 
teeth of the type of H. anthonyi. There is a small fold on the anterior 
side of the hypoconid in a posterior premolar. The size of the crowns 
in Hipparion condoni suggests a type near the size of the Ironside 
specimen. Other characters indicate that the two forms are not 
specifically identical. 

From such evidence as may be obtained from the single tooth 
available it may be concluded that no. 22351 from Ironside represents 
a species distinct from any thus far described in the Great Basin 
region and that the stage of evolution is not far from that of the 
Ricardo hipparions. This would indicate that the deposits near Iron- 
side are of early Pliocene or late Miocene age. 

A single fragment, no. 22355 (fig. 2), of an upper cheek-tooth from 
the deposits near Ironside consists of a cement-filled fossette with the 
enamel wall. The wall shows very strong plications, eight folds on 
one side and four on the other. This fragment evidently represents 
a Hipparion form similar in character to H. anthonyi, and it may be 
considered to represent that species. The form of fossette and degree 
of complication of the enamel folds bordering it suggest the character 
of the Rattlesnake Pliocene species with most complicated enamel. 



Comparative Measurements 



H. m. callodonte 
No. 21311 
Ricardo 
28.4 
12. 



P5, anteroposterior diameter 

Pg, transverse diameter across hypoconid 



No. 22351 
Ironside 
27.8 mm. 
11.4 



134 



University of California Publications in Geology 



[Vol. 10 



TETR ABELODON ?, sp. 

A single lower cheek-tooth (no. 22883, fig. 3) found by Mr. Elmer 
Molthan one quarter of a mile south of locality 3037 near Ironside, 
Oregon, represents a large mastodontine form presumably from the 
same formation and from approximately the same horizon as the teeth 




Fig. 3. Tetrabelodon?, sp. Lower cheek-tooth, no. 22883, natural size. Outer 
and occlusal views. From late Tertiary beds near Ironside, Oregon. 

described as Hipparion anthonyi. The low conical tubercles are 
lightly connected transversely, and a few accessory tubercles are situ- 
ated in the transverse valleys. This form resembles a type found in 
Great Basin beds referred to Pliocene or late Miocene, but the Pliocene 
mastodontine forms of this province are as yet very imperfectly 
known, and until further comparative studies have been made it is 
not possible to make satisfactory determination of the species repre- 



1916] Merriam: Mammalian Remains from Ironside, Oregon 135 



sented by this specimen. It is, however, of importance to place on 
record the occurrence of this form. 

Two fragments of mastodontine teeth from locality 3037 repre- 
sent a type which does not give evidence of differing from specimen 
22883 found by Mr. Molthan. 

Measurements op No. 22883 

Greatest anteroposterior diameter 145 mm. 

Greatest transverse diameter across second transverse crest from an- 
terior end 62. 



EHINOCEEOTID, indet. 
A fragment of an upper rhinoceros cheek-tooth from locality 3037 
represents an indeterminate form. It is possible that future studies 
with the use of exceptionally good material for comparison may make 
possible an approximate determination of this tooth. For the present- 
it is desirable to record the occurrence of rhinocerotid remains at this 
locality. 

Transmitted December 18, 1916. 




UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF v 

GEOLOGY 

Vol. 10, No. 10, pp. 137-164, 8 text-figures Issued February 5, 1917 



RECENT STUDIES ON THE SKULL AND 
DENTITION OF NOTHROTHERIUM 
FROM RANCHO LA BREA 



BY 

CHESTER STOCK 



UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 10, pp. 137-164, 8 text-figures Issued February 5, 1917 



RECENT STUDIES ON THE SKULL AND 
DENTITION OF NOTHROTHERIUM 
FROM RANCHO LA BREA 

BY 

CHESTEE STOCK 

CONTENTS 

PAGE 



Introduction 137 

Cranium 139 

Mandible 148 

Dentition 151 

Review of Species 157 

Relationships of Genus 162 

Conclusions 163 



INTRODUCTION 

The first remains of the Pleistocene ground-sloth Nothrotherium 
(Coelodon) were found in a Brazilian cavern by P. W. Lund, 1 who 
believed the fossils to represent a small Megatherium. Lund later 
recognized the distinctness of the form and established the genus 
Coelodon. 2 Material belonging to a young individual subsequently 
collected by Lund was fully described and compared with other 

1 Lund, P. W., Om Huler i Kalksteen i det Indre af Brasilien, der Tildeels 
Indeholde Fossile Knokler, Pt. 1, Kgl. Danske Vidensk. Selskabs Skr., 4 Raekke, 
naturvidenskabelige og mathematiske AfhandL, 6 deel, pp. 207-248, 2 pis., 1837. 

2 Lydekker in ]889 replaced Coelodon Lund by Nothrotherium, stating that 
the former name was preoccupied. Recently Winge (E Museo Lundii, vol. 3, 
pt. 2, pp. 136-138, 287-288, pis. 24-25, 1915) has returned to Lund's original 
designation of the genus. 

The name Coelodon was first used by Audinet-Serville (Ann. Soc. Entom. 
France, L832, p. 164) for a genus of long-horned, wood-boring beetles (Fam. 
Cerambycidae) from Senegal. Since Lund did not propose Coelodon for the 
ground-sloth from the Brazilian cavern until 1839, there is no question as to 
priority. 



138. University of California Publications in Geology [Vol.10 



Pleistocene genera by Reinhardt 3 in 1878. The relationship of this 
genus to the Miocene ground-sloths of Patagonia has been discussed 
by Scott 4 and Ameghino. 5 

It is of considerable interest to note that Nothrotherium has only 
recently been definitely recognized, although tentatively recorded by 
Sinclair in 1905, as a member of the North American Pleistocene 
fauna. Its distribution over the northern continent, as indicated by 
the known occurrences in Pleistocene deposits of California and 
Texas. 7 is apparently much more restricted than that of Megalonyx 
and Mylodon. It seems not improbable that the genus, when known 
more completely, will be recognized in other Pleistocene faunas. 
Among the Rancho La Brea edentates, the nothrotheres rank next to 
the mylodont sloths in abundance, but are present in far smaller num- 
bers than the latter. Curiously enough, Nothrotherium is represented 
in the asphalt by a greater number of individuals than Megalonyx. 

The Museum of History, Science and Art of Los Angeles contains 
in its Rancho La Brea collection eight more or less complete crania 
with fragments of perhaps four other individuals. A number of 
mandibles are also available. All of the better preserved skulls are 
much larger than Reinhardt 's specimen and belong to adult or nearly 
adult individuals. Associated with the skulls is one nearly complete 
skeleton and many separate parts of skeletons. In the present pre- 
liminary discussion only the skull of the nothrotheres is considered. It 
is planned to give a fuller account of Nothrotherium from the asphalt 
beds in which all the material of the genus will be reviewed. 

The present report is based entirely on material contained in the 



a Beinhardt, .1., Kaempedovendyr-Slaegten Coelodon, Vidensk. Selsk. Skr., 
5 Raekke, naturvidenskabelig og mathematisk Afhandl., vol. 12, 3, pp. 253-349, 
5 pis., Copenhagen, 1878. 

4 Seott, W. B., Kept. Prin. Univ. Exp. Patag., 1896-1899, vol. 5, Gravigrada, 
1903-1904. 

•"> Ameghino, F., Notas sobre una pequefia colece.ion de huesos de mamiferos 
procedentes de las grutas ealeareas de Iporanga en el Estado de Sao Paulo- 
Brazil, Revista do Museu Paulista, vol. 7, pp. 74-119, 1907. 

11 Sinclair. W. J., New mammalia from the quaternarv eaves of California, 
Univ. Calif. Publ. Bull. Dept. Geo]., vol. 4, pp. 153-155, pi. 23, figs. l-5a and 8, 
1 905. 

' In a discussion of the quicksilver deposits of the Terlingua district, Brewster 
County, Texas. H. W. Turner makes mention (Economic Geology, vol. 1, p. 275, 
1906) of the finding of ground-sloth remains in a fissure deposit. This material 
was submitted to Professor J. C. Merriam, who identified several teeth as 
belonging to Nothrotherium. The specimens were placed in the Museum of the 
California Academv of Sciences in San Francisco, where they were destroyed 
by the fire of April 18, 1906. 

'Recently O. P. Hay has described (Proc. U. S. Nat. Mus., vol. 51, pp. 116-123, 
pis. 6 and 7, 1916) a new species, Nothrotherium texanum, from the Pleistocene 
of Texas. 



1917] 



Stock: Skull and Dentition of Nothrotherium 



139 



Museum of History, Science and Art of Los Angeles. For the privilege 
of studying this remarkable collection of nothrotheres, I am very 
greatly indebted to Director Frank S. Daggett, Thanks are due also 
to the other members of the Museum staff for many courtesies extended. 
I am obligated to Professor John C. Merriam for assistance and much 
friendly advice and criticism during the progress of the research on 
the Rancho La Brea edentates. 

The drawings reproduced in this paper have been prepared by 
Mrs. Louise Nash. 

CEANIUM 

The largest available skull of Nothrotherium from Rancho La Brea 
is approximately as long as a skull of Megalonyx jeffersoni described 




Fig. 1. Nothrotherium shastense Sinclair. Cranium, no. 208 M. Ii. S. A., 
superior view, X %. Rancho La Brea Beds, California. 

by Leidy. 8 With this exception the specimens from the asphalt beds 
are all somewhat shorter than either M. jeffersoni or M. leidyi. In 
marked contrast to Megalonyx, however, is the relative slenderness of 
skull in Nothrotherium. In this respect the latter genus more closely 
resembles the Miocene Megalonychidae and Planopsidae," from which 
it has also deviated less than Megalonyx in general shape of skull. 
Contrasted with Planops, one of the largest of the Santa Cruz Gravi- 
gracla, the skull of the Pleistocene genus is distinctly larger. 

s Leidy, J., A memoir on the extinct sloth tribe of North America, Smithson. 
Contrib. Knowl., vol. 7, 1855; see measurements of the Dickeson specimen, p. 13. 

8 Scott, W. B., Rept. Prin. Univ. Exp. Patag., 1896-1899, vol. 5, p. 164, fig. 16, 
1903. 



140 University of California Publications in Geology [Vol. 10 



Nothrotherium differs from Megalonyx and agrees with Hapalops 
in the long and slender muzzle (fig. 1). In no. 632 10 the anterior ends 
of the maxillaries are noticeably flared. This character is less appar- 
ent in no. 633 and may be but little developed as in no. 634. The 
nasals are long and may be more decidedly arched in some skulls than 
in others. In no. 632 the fronto-nasal suture is convex posteriorly, 
thus resembling most species of Hapalops. This suture may, however, 
vary in Nothrotherium. It may be decidedly V-shaped as in no. 633, 
but in this specimen the original suture appears to have been some- 
what in advance of the present separation. In no. 633 the nasals 
have apparently fused with the frontals, a secondary or pseudo fronto- 
nasal suture developing posterior to the original suture. A similar 
abnormality in the separation between nasal and frontal has been 
noted in skulls of Mylodon harlani from Rancho La Brea. 11 

In some specimens the lachrymal is not as prominent in superior 
view as in species of Hapalops, but its canal is very much in evidence. 
In Megalonyx the lachrymal and its canal are apparently not to be 
seen in dorsal aspect. The postorbital processes of the frontals may 
be very blunt in some specimens of Nothrotherium, thus being more 
as in Megalonyx and differing from Megatherium. Between and 
slightly posterior to the supraorbital borders, the frontals sag in the 
middle line. This sag is perhaps most evident in the largest specimen, 
no. 634. and in skull 203. In skull 15 it is practically absent. 

The temporal ridges are but faintly marked in all specimens from 
Rancho La Brea. Nothrotherium thus resembling the Miocene Mega- 
lonychidae. At the coronal suture where the crests approach each 
other most closely, the distance between them may vary. There is 
never a pronounced sagittal or lambdoidal crest present as in Mega- 
lonyx. In front of the weak lambdoidal crest the dorso-lateral surface 
of the parietal may sag slightly. This sag is distinctly developed in 
no. 633 where it reaches the median dorsal suture of the cranium, or 
it is hardly discernible, as in skulls 632 and 634. In all skulls of 
Nothrotherium the supraoccipital is more prominent in superior view 
than in Megalonyx. It is very evident in skull 208 (fig. 1). 

As indicated in a former paper, 12 the Brazilian species described 

10 All numbers used in the following comparisons in this paper, unless other- 
wise stated, are the catalogue numbers of specimens in the Museum of History, 
Science and Art of Los Angeles. 

11 Stock, C, Skull and dentition of the Mylodont sloths of Eancho La Brea, 
t T niv. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 322, 1914. 

is Stock C, Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, p. 343, 1913. 



1917] 



Stock: Skull and Dentition of Nothrotherium 



141 



by Reinhardt 13 differs noticeably from the Californian form in dorsal 
contour of skull (fig. 2). It is possible that this difference is in part 
due to age, but it is probably a specific distinction. In Hapalops 
longiceps the frontal is more elevated than the parietal, while in H. 
vulpiceps and H. graciUdens the reverse is true, the parietal being 
much more highly vaulted than the frontal. In the elevation of the 
frontal the Rancho La Brea species of Nothrotherium approaches 
Planops most closely. MegaLonyx differs from its Pleistocene con- 
temporary in the straight dorsal contour of the skull. 

The zygomatic process of the squamosal is long and slender. It is 
relatively longer than in H. longiceps. In skull 15, used as the type 
in the first description 14 of the species from Rancho La Brea, this 



Fig. 2. Nothrotherium sliastcnse Sinclair. Cranium, no. 208 M. H. S. A., 
lateral view, X %• Rancho La Brea Beds, California. 

process is broken. The malars have been preserved in several skulls, 
notably in no. 208, where they are firmly attached at the base to 
lachrymal and maxillary. The malar resembles Hapalops in slender- 
ness, and, as in that genus, is not fused with the zygomatic process of 
the squamosal. It differs from H. longiceps in (1) its relatively shorter 
anteroposterior extent, (2) an absence of a marked outward flare of 
the infraorbital border, (3) a shorter dorsal prong, but deeper notch 
for the zygomatic process of the squamosal, and (4) a relatively longer 
and more slender ventral prong. 

13 Reinhardt, J., Kaempedovendyr-Slaegten Coelodon, Vidensk. Selsk. Skr., 
5 Raekke, naturvidenskabelig og mathematisk Ar'handl., vol. 12, 3, pp. 253-310, 
5 pis., Copenhagen, 1878. 

i-t Stock, C, op. cit., pp. 342-350, 1913. 




142 University of California Publications in Geology [ Vol.10 



In Megalonyx the zygomatic process of the squamosal is much 
heavier than in Nothrotherium. In M. leidyi 15 and in Megatherium 
american um ie this process has completely fused with the malar. The 
postorhital border of the malar is decidedly more curved in M. leidyi 
than in Nothrotherium. The ventral prong is also relatively more 
slender at the base in M. leidyi. 

The parietal sends downward and forward a narrow extension 
which usually meets the lateral portion of the alisphenoid. Occasion- 
ally this extension docs not reach the alisphenoid but is interrupted 
by the frontal. The foramen rotundum and foramen ovale open 
together as in Hapalops and may form a slightly larger orifice than the 
foramen lacerum anterius. The orbitosphenoid is not clearly defined 
by suture. The optic foramen lies at the posterior end of a groove 
which widens anteriorly, and may lie somewhat obscured by the over- 
hanging of the frontal. 

The premaxillaries, although originally present in the Rancho La 
Brea skidls. have not been thus far recognized in the collections. 
Their articulating surfaces on the maxillaries reveal some interesting 
peculiarities. On each side of the small median V-shaped notch the 
maxillary is thickened, especially the palatal portion. This thickening 
of the maxillary extends well up along the sides of the external narial 
opening, in some skulls reaching nearly halfway to the top of the 
orifice. In the Brazilian species described by Reinhardt, the pre- 
maxillary is shown as a Y-shaped element. In Reinhardt 's figure 17 
the median arm of the posterior end is seen to be short, while the 
lateral arm is longer and appears to curve upward. This apparently 
corresponds with the thickening of the maxillary at the inferior 
external angle of the narial opening. The anterior arm of the pre- 
maxillary was presumably not very long in the Nothrotherium from 
the asphalt beds. 

In Hapalops a similar Y-shaped premaxillary is present. The 
articulation of this element with the maxillary may somewhat resemble 
that in the Rancho La Brea genus. The articulation between pre- 
maxillary and the end of the palatal portion of the maxillary is not as 
extensive in Nothrotherium as in Hyperieptus. In the Miocene 

is Lindahl, J., Description of a skull of Megalonyx leidyi, n.sp., Trans. Amer. 
Philos. Soc, vol. 17, n.s., pp. 4-6, pi. 1, 1893. 

1,1 Owen, R., On the Megatherium (Megatherium americanum, Cuvier and 
Blumenbach), Ft. 3, The skull, Philos. Trans. Roy. Soc. Lond., vol. 146, pi. 21, 
fig. 1, 1856. 

it Reinhardt, J., op. tit., pi. 1, fig. 3, 1878. 



1917] 



Stock: Skull and Dentition of Nothrotherium 



143 



Planops, according to Scott, "the premaxillae were evidently large, 
the facets for them upon the maxillaries being of uncommon size, 
while the median notch for the spines is a characteristically deep and 
narrow V." 18 In Megalonyx jeffersoni Leidy describes 1 " the pre- 
maxillaries as "simple, oblong, quadrilateral plates, a little more than 
two inches in depth, and three quarters of an inch in breadth." 

Owing to the slenderness of the muzzle, the anterior aspect of the 
skull of Nothrotherium is decidedly unlike that in Megalonyx. In 
M. jeffersoni, according to Leidy, "The end of the face is relatively 
narrower and higher than in Mylodon; and in outline is more ver- 
tically oblong quadrilateral, with the upper margin convex and the 
sides nearly vertical."- In Nothrotherium where the first or canini- 




Fijr. 3. Nothrotherium shastense Sinclair. Cranium, no. 208 M. H. S. A., 
inferior view, X %. Raneho La Brea Beds, California. 

form tooth is absent, the anterior end of the skull is nearly round or 
oval. The external narial opening is relatively wide transversely as 
contrasted with the height. The lateral walls show no indication of 
notching as in Megatherium. With the disappearance of the canini- 
form tooth in Nothrotherium the depression of the lateral wall of the 
maxillary anterior to 1VP becomes nearly obsolete. This depression 
is better developed in Hapalops and is very pronounced in Megalonyx. 

The palate (fig. 3) anterior to may be approximately twice 
as wide as between the tooth-rows. The lateral borders of the eden- 
tulous portion of the palate may be nearly straight as in no. 632 or 

is Scott, W. B., Kept. Prin. Univ. Exp. Patag., 1896-1899, vol. 5, p. 322, 1904. 
io Leidy, J., op. cit., p. 11, 1855. 
20 Leidy, J., ibid. 



144 University of California Publications in Geology [Vol. 10 



they may become convex outward as in skull 634. In the outwardly 
convex borders of the palate no. 634 resembles greatly species of 
Hapalops in which the first or caniniform tooth is some distance pos- 
terior to the end of the skull. In particular does it resemble a skull 
of Planops longirostris illustrated by Scott. 21 In Megalonyx the 
palate in front of M- is relatively shorter and the sides diverge 
anteriorly more than in Nothrotherium. 

The palate is .flat or somewhat convex. It is considerably pitted 
with large and small foramina, resembling Hapalops in this respect 
more than Planops. , On either side of the raised median suture and 
between the tooth-rows extends a series of large foramina. From the 
most anterior of these, which occupy a position approximately at the 
middle of the predental portion of the palate, widening grooves extend 
forward to nearly the front end of the skull. Scott describes the 
edentulous space in H. longiceps as having "a well-defined groove on 
each external side, with raised outer border." 22 In no. 634 the 
anterior openings of the palatine canals lie between the points of 
greatest outward curvature of the margins of the palate. In skull 166 
they open on the surface of the palate much more posteriorly, or 
nearer M-, than, in the remaining skulls. 

The palatine suture, which for some distance parallels the margin 
of the postpalatine notch, meets the middle line of the palate between 
or behind the posterior ends of M-. The postero-internal border of the 
alveolus for M- may be somewhat elevated, causing the palate to become 
transversely concave in this region. The posterior opening of the 
palatine canal opens at the anterior end of an elongate pit. The latter 
is situated on the palatine shelf bordering the postpalatine notch, and 
its anterior border is usually posterior to the last superior tooth. The 
pit may, however, extend well along the inner side of M-. At the 
posterior end of the elongate pit a second opening leads to the lateral 
cranial wall. The large foramina, extending in a row on either side 
of the median suture of the palate, open directly into the palatine 
canals. 

The postpalatine notch is always more acute than in the skull 
described by Reinhardt, and apparently reached slightly farther for- 
ward in the Rancho La Brea species. Its position is, however, well 
posterior to MA In Planops magnus Scott states that "The posterior 
nares do not extend so far forward as in most of the contemporary 

21 Scott, W. B., op. cit.. pi. 59, fig. la, 1904. 

22 Scott, W. B., op cit., p. 185, 1903. 



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Stock: Skull a)id Dentition of Nothrotherium 



115 



Gravigrada, the front margin being a little behind - . . ."- :t The 
pterygoid plates continue backward from the shelf, formed by palatine 
and in part also by maxillary, along either side of the postpalatine 
notch. On these plates the inferior border is broadly rounded while in 
Megatherium it is angnlate. In the Rancho La Brea Nothrotherium 
the plates are very similar to those in Bernhardt 's specimen, and pos- 
teriorly are seen to enlarge into great bullae as in the latter form. 
These bullae differ decidedly from those shown by Reinhardt in being 
pierced along their inner ventral wall by a large and elongate orifice. 
Between the outer border of this opening and the inferior border of 
the pterygoid plate a broad groove extends from the outer posterior 
to the inner anterior side, diagonally across the inflated portion. The 
posterior border of the pterygoid may approach the occipital condyles 
very closely, thus differing decidedly from Megalonyx. 

The inflated pterygoids are perfectly preserved in skull 208 (fig. 3) 
in which specimen they swell outward somewhat below the base of the 
zygoma and behind the glenoid fossa. They are much better preserved 
than in the skull, no. 15, originally described. In an earlier note on 
the skull of the Rancho La Brea Nothrotherium the writer inadvert- 
ently referred to these structures as tympanic bullae, stating that 
Reinhardt considered them as such in the Brazilian species. In this 
respect unfortunately Reinhardt has been misquoted, as he distinctly 
and correctly interprets them as being merely inflations of the posterior 
portions of the pterygoid. The pterygoid bullae in all the skulls except 
one are large. In no. 313, which is the smallest of the eight nearly 
complete skulls contained in the Museum of History, Science and Art 
of Los Angeles, and evidently belongs to a somewhat younger indi- 
vidual, the posterior inflation of the pterygoid is exceedingly small 
and is restricted to the extreme posterior end of the pterygoid. The 
ventral opening of the bulla is also small. Between the cavity and 
the descending plate, the pterygoid is thickened in this specimen. 

In Hapalops longiceps, according to Scott, "The pterygoids are 
narrow, inconspicuous plates, closely applied to the descending pro- 
cesses of the alisphenoids, and not in the least like the swollen, bulla- 
like bones of Nothrotherium, which Reinhardt has described ( '78, 
336). " 24 Structures comparable to the pterygoid bullae of Noth- 
rotherium and occupying a similar position are absent in Megalonyx. 
Lindahl, however, records that in M. leidyi, "capacious air sinuses 



23 Scott, W. B., op. cit., p. 326, 1904. 
2-4 Scott, W. B., op. cit., p. 185, 1903. 



146 University of California Publications in Geology [Vol. 10 



extend backward in the root of the pterygoid (PI. Ill), and branch 
off from there forward into the alveolar wall of the maxilla." 2 '' An 
extensive inflation of the pterygoid in skulls of the tree sloths 
Choloepus and Hemibradypus has been noted by Anthony. 20 With 
reference to the air sinuses in the skull of the former genus, he states : 

Le sinus sphenoidal s'etend lateralement a l'interieur des pterygoi'des, se 
prolonge dans le temporal, envahissant la base de l'apophyse zygomatique et 
venant presque au contact des prolongements lateraux du sinus frontal. Le 
crane osseux presente un orifice situe a la face interne et anterieure de chaque 
pterygoi'de et qui conduit dans ce sinus.- 7 

Nothrotherium therefore resembles Choloepus very closely not only 
in the large size of the pterygoid inflation but also in the presence of 
an orifice perforating the inner wall of the pterygoid. 

The alisphenoid forms not only the roof of the pterygoid bulla but 
the dorso-internal wall as well. In some skulls an internal continua- 
tion of the vacuity of the pterygoid extends toward the middle line. 
In skull 634 this extension, lying below the ventral surface of the 
basisphenoid, is separated from its fellow of the opposite side by a 
median partition only 2 mm. in thickness. The development of these 
internal sinuses varies from the extreme case seen in no. 634 to their 
entire absence as in skull 15. 

The basisphenoid is concave transversely and tapers towards the 
anterior end where the pterygoid bullae approach each other most 
closely. 

The basioecipital in most skulls is short, relatively much more so 
than in Megalonyx. The tympanic, as seen in no. 208, resembles 
Rapalops in the incomplete, irregular circle of bone which encloses 
ventrally the large external auditory meatus. Anteriorly the tympanic 
may touch the dilated wall of the pterygoid. Posterior to the 
tympanic is the stylo-hyal process with its ovoid depression. It is 
situated much closer to the occipital condyle than in Megalonyx. 
The small condylar foramen lies in a pit and may be entirely hidden 
by the border of the occipital condyle. In Hapalops and especially 
in Megalonyx this foramen is well in front of the occipital condyle. 

The paroccipital process, as in Hapalops, is inconspicuous, being 
much less prominent than in Megalonyx. Between it and the stylo- 
id Lindahl, J., Description of a skull of Megalonyx leidyi, n.sp., Trans. Amer. 
Philos. Soc, vol. 17, n.s., p. 7, 1893. 

- r > Anthony, E., Eecherches anatomiques sur les bradvpes arboricoles, etc., 
Ann. Sci. Nat., ser. 9 (Zool.), vol. 9, pp. 157-285, pis. 2-6, 1909. 
27 Anthony, R., ibid., p. 178, 1909. 



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Stock: Skull and Dentition of Nothrotherium 



147 



hyal process is a deep groove which reaches the occiput and extends 
for a short way along its lateral border. The position of the occipital 
condyles with reference to the pterygoid bullae has already been 
noted. The condyles in ventral aspect are not obliquely placed as in 
Megalonyx, and project posteriorly much less than in that genus or in 
Megatherium. They may be widely separated as in no. 313, or much 
closer together as in no. 203. By far the greater articulating surface 
of the condyles is directed downward, forward and outward. Leidy 
states that in Megalonyx the articulating surface of the condyles is 
bent at about the middle. In no. 633 the dorsal portion of the outer 
border of the condyle is curiously flattened by a rough and rather 
extensive surface. The foramen magnum may be transversely oval 
in shape. It opens more downward than in Megalonyx. 

The base of the zygoma is long, and the glenoid fossa is somewhat 
concave transversely. The zygomatic process is quite like that in 



Fig. 4. Nothrotherium shastense Sinclair. Cranium, no. 208 M. H. S. A., 
posterior view, X %. Rancho La Brea Beds, California. 

Ha pal ops, differing from Megalonyx in not projecting so far from 
the side of the skull. 

As in Miocene genera, the occiput of the Rancho La Brea Nothro- 
therium is nearly vertical or inclined slightly beyond the occipital 
condyles. The supraoccipital forms usually an extensive, forwardly 
inclined surface. In posterior view (fig. 4) the condyles are seen to 
be as a rule more widely separated than in Hapalops. In no. 203 
their position is more as in the latter genus. The posterior face of the 
condyles is relatively smaller than in Hapalops. The dorsal lip of the 
foramen magnum is notched at the middle only in skulls 15 and 166. 
The median vertical ridge of the occiput does not usually reach the 
foramen magnum. It is sharp below but greatly broadens dorsally on 
the surface of the supraoccipital. Where the vertical surface of the 
occiput meets the forwardly inclined surface a heavy, rugose, trans- 




148 University of California Publications in Geology [Vol. 10 



verse ridge is formed as in Megalonyx. This ridge swings outward 
and downward and in some skulls is directly connected with the pos- 
terior surface of the stylohyal process. The crest of the occiput is 
not prominent except along its lower end. 

< < < < ■< <i 

co g co g te g co g cog cog 

• u • u • u • u ■ u < u 

KM Wee Em Km Mm 

Measurements of Cranium g ■ a Uu s £^ a S^-a a « 

gSj cSj crfj sS^j 

CO O IcCOc to CO o b p1 O w^O m^O 

cs co ds o xl n ~ c;co^: rt^x: <3 co ,n 

X H O ^ L' ,i= CO Cj x- CO U r-CCO CO C 

» . « to . a m.c » . c m.c IZ.c 

.©« .Oct . o ci . o ee .ocs .oca 
fe^CS fcfctf 

Length from anterior end of maxillaries to 

posterior end of occipital condyles 320 mm. 309 302 313.6 330 

Length from anterior end of nasals to pos- 
terior end of supraoccipital 339.8 336.3 320.4 333.3 339.5 352 

Length of palate, from anterior end of 

maxillaries to postpalatine notch 141.7 0135.4 127 131 144 

Greatest width of palate anterior to M2 45.8 46.2 42.9 42.9 48 

Width of palate between alveoli of M.- 22 23.6 21.4 20.6 24 21.8 

Greatest width of pterygoid bulla 41.4 43.2 17.4 o37.9 37.4 a41.6 

Greatest length of internal orifice of ptery- 
goid bulla 37.6 38.2 21.7 36.7 30.5 

Greatest width of internal orifice of ptery- 
goid bulla 14.4 a8.5 12 

Least distance between pterygoid bullae 

Mastoid width above stylohyal processes...- 112.8 118.4 

Greatest width across occipital condyles .... 75.4 78 

Transverse diameter of foramen magnum, 

internal measurement 33.5 29.6 

Dorso-ventral diameter of foramen mag- 
num, internal measurement 28.7 24.9 

Height of oeciput from plane of basioccipital 

to lambdoidal suture 79.6 87.7 

Greatest width of muzzle at anterior end.... 70 78.2 

Length of nasals 114.5 114.7 

Greatest width above orbits 103.2 104.9 

Least width behind orbits, in region of 

coronal suture 78.2 80 

Width, measured across anterior ends of 

zygomatic processes of squamosals 153.8 153.5 

Least distance between outer sides of ptery- 
goid plates 61 56.4 

Greatest height from ventral border of ptery- 
goid plate to highest elevation of frontals 134.7 139.9 a!30.3 

a, approximate. 





23.3 


21.3 


21.8 


110.5 


114 


114 


120.6 


78.4 


74.9 


78.4 


81.1 


30 


32 


31.8 


36 


26.3 


24.2 


24.2 


29.5 


80.7 


78.5 


76.5 


85 


65.5 


73.9 


73.4 


73.4 


130.8 


111.9 


134.3 


122.4 


98.3 


104.3 


102.9 


112.9 


82 


78.5 


77 


83.8 



MANDIBLE 

The most striking characteristic of the lower jaw of Nothrotherium 
is its great similarity to that of Hapalops. The former genus in this 
regard is decidedly closer to the Miocene form than to its Pleistocene 



1917] Stock: Skull and Dentition of Nothrotherium 149 



contemporary, Megalonyx. In general structure of 1 mandible Nothro- 
therium bears the same relation to Hapalops as Megalonyx does to 
Eucholoeops. The lower jaw of an apparently adult individual, no! 
208, of the Rancho La Brea species is approximately twice as large 
as that in Hapalops longiceps. Although the mandible may very 
closely approach Megalonyx in total length, yet it differs from that 
genus in its very decided slenderness. 

In both Hapalops and Nothrotherium the predentary portion of 
the jaw is produced anteriorly into a long beak which in the latter 
genus is also deeply concave. The edentulous beak or spout (fig. 5) 
is much more elongate than in Megalonyx. The anterior end may be 
rather acutely tapering as in no. 208 or rounding as in no. 456. 




Fig. 5. Nothrotherium shastense Sinclair. Mandible, no. 166 M. H. S. A., 
superior view, X %. Rancho La Brea Beds, California. 

As pointed out by Scott, the lower border of the ramus in Nothro- 
therium is less sinuous than in Hapalops. In the former genus it forms 
an even convexity which reaches its maximum development below 
the third inferior tooth. This border is more strongly convex than 
in Megalonyx, but decidedly less so than in Megatherium. The inferior 
border posterior to the tooth series and reaching to the end of the 1 
angular process is less decidedly concave in Nothrotherium than in 
Hapalops. 

The symphyseal keel is long and sharp, but not as prominent as in 
Megalonyx. Usually but a single mental foramen is present. In no. 
456, however, a small opening is situated slightly above and posterior 
to the mental foramen of the right side. The horizontal limb of the 
ramus (fig. 6) is noticeably of less height, especially in the anterior 
region, and less robust than in Megalonyx. With the disappearance 



150 University of California Publications in Geology [Vol. 10 



of the first tooth in Nothrotherium the deeply concave, outer wall of 
mandible between M T and Mj, occurring in Hapalops and Megalonyx, 
becomes greatly reduced and may be entirely absent as in no 166. 
There are frequently two foramina representing the postero-external 
opening of the dental canal in the Raneho La Brea species. In no. 208 
two foramina are present on the left ramus and one on the right, an 
occurrence similar to that in a skull of Hapalops longiceps, no. 15523 
Prin. Univ. Coll., wbile in no. 456 from Raneho La Brea there are 
two foramina on each side. The anterior foramen is situated on the 
outer surface of the ramus opposite the last inferior tooth and the 
second opening is at or slightly above the base of the ascending process. 

The eoronoid process arises well to the outer side of M 3 as in 
Hapalops. but it is relatively smaller than in the latter. It may be 




Fig. 6. Nothrotherium sJiastense Sinclair. Mandible no. 166 M. IT. S. A., 
lateral view, X %. Raneho La Brea Beds, California. 

broad as in no. 456 or rather narrow. The sigmoid notch, due to the 
high position of the condyle above the tooth row in Nothrothevium, 
is relatively much smaller than in the Miocene genus. In no. 208 the 
condyle in dorsal view has much the shape seen in Hapalops longiceps. 
In no. 456 and no. 418 the condyle has a greater oblique diameter and 
is more slender than in no. 208. The ventral notch between cond.yle and 
angle is relatively wider than in Hapalops, while the angular process 
in some specimens from the asphalt extends posteriorly as a more 
slender hook than in H. longiceps. The angle of the jaw is much more 
slender in Nothrotherium than in Megalonyx. In M. jeffersoni the 
eoronoid and angle are more nearly equally spaced on either side of 
the condyle than in the Raneho La Brea genus. The inferior border 
of the angle is deflected inward, forming a more pronounced shelf 
than in Megalonyx. 



1917 



Stock: Skull and Dentition of Nothrotherium 



151 



Km 

Measurements of Mandible" ^ „ 

CtflJ 

e 

2 So 

, O cz 

Length from anterior end of sym- 
physis to posterior end of condyle 275 mm. 

Distance from anterior end of sym- 
physis to anterior border of 
alveolus for M 5 100.9 

Distance from posterior border of 
alveolus for Mj to posterior end 
of angle 121.2 

Greatest length of symphysis 90.4 

Greatest depth between Mj and M3, 

measured normal to tooth-row.... 56.6 

Least height posterior to Mj 43 

Greatest height from angle to coro- 

noid process 106.6 

Height of condyle above ventral 

border of angular process 79.7 

Thickness of horizontal ramus at M3 27.2 

Distance between inner alveolar 
borders of fourth cheek-teeth .... 33 

* Where association of mandible with cranium 
separate number. 

t This mandible may belong to cranium 313. 
a, approximate. 



M 00 o 
~ O J3 



30. 



w p 



■£ 00 o 
J3 ■* a 



m i 
Wffl 



w p 



tS® 2 

^ CO v 



. O « . O « . o « 

2; pi y y Pi y y, Pi 



((260. 



284.4 a267 



196.2 a96.8 104. 



1 09.3 



134.6 al20 124.3 117.1 
90.3 ((82.9 90.2 87 



60.6 
47.5 

121.4 



29.3 



54.2 
42 



56.1 53 
44.8 38.6 

all3.8 nlOl.7 



26.7 28.2 25.3 



24.3 



Us 



y.'ypi 



61.3 
46.8 



; . 

1%S 



. o « 

y ypi 



61.6 
47.5 



26.4 26.8 



is in doubt, the former is listed under 



DENTITION 

The dental formula in the Rancho La Brea Nothrotherium as in 

the Brazilian species is |-~| . In possessing a reduced dentition. 

Nothrotherium differs markedly from the certainly known Miocene 
Megalonyehidae and Planopsidae as well as from the Pleistocene genera, 
Megalonyx and Megatherium. All the teeth are considerably smaller 
than in Megalonyx. The external layer of cement on the teeth may be 
only as thick relatively as in Hapalops. 

Superior Series. — The tooth-rows extend very nearly parallel, the 
palate increasing slightly in width between the fifth cheek-teeth. The 
teeth are more closely spaced than in Miocene genera. In the Rancho 
La Brea species the largest interspace occurs between the alveoli of 
M- and M-. Reinhardt states that in the Brazilian species of Nothro- 
therium the teeth are equally spaced. 

As in the various species of Santa Cruz ground-sloths the differ- 
entiation of the superior molariform teeth into a small M-, much 



152 



University of California Publications in Geology [Vol. 10 



larger M- and M-, and a M- greatly compressed anteroposteriorly, 
occurs also in Nothrotherium although the distinction between Inl- 
and M- or M- is not as marked in the former as in the latter. The 
teeth in Nothrotherium are noticeably more complex. This is indi- 
cated by the presence of distinct, median vertical grooves on the 
outer faces of M-, M- and M-, and to a less extent also on the inner 
faces. Even M-, which is much more compressed anteroposteriorly 
than the other superior teeth, shows a distinct groove on the outer 
face and a much more faintly developed one on the inner. Nothro- 
therium, therefore, differs from Megalonyx in which such distinct 
lateral grooves are lacking on these teeth. In Hapalops indiffercns the 
vertical grooving on the outer face of M-, M- and M- has been noted by 
Scott in some specimens. In describing the corresponding teeth, as 




Fig. 7. Nothrotherium shastense Sinclair. Right, superior, dental series no. 
208 M. H. S. A., occlusal view, natural size. First tooth to the right is M ? . 
Rancho La Brea Beds, California. 

well as M-, in II. elongatus, Scott 28 states that "the vertical groov- 
ing of these teeth appears to be very capriciously present or absent." 
Judging from the appearance of the occlusal surface, the outer com- 
pact layer of dentine in all the superior teeth of Nothrotherium is 
best developed on the anterior and posterior surfaces and least 
developed on the outer and inner sides. In M-, M- and M 4 this layer 
is slightly thicker on the outer than on the inner surface. In M- the 
layer is thickest on the posterior face, while on the outer and inner 
faces it is of equal thickness. 

M- is smaller than M- and M 1 . Contrasted with the latter teeth, 
M- is relatively narrower transversely in Nothrotherium than in most 
species of Hapalops. It is relatively longer anteroposteriorly than in 
the latter genus. The tooth may be trapezoidal in shape, with anterior 
and posterior faces parallel as in no. 313, or these faces may converge to 
the outer side as in skull 208 (fig. 7). The anterior and posterior faces 
are nearly flat and the angles are well rounded. M- thus differs from 

as Scott, W. B., op. tit., p. 218, 1903. 



1917] 



Stock: Skull and Dentition, of Nothrotheriwn 



153 



the corresponding 1 tooth in Megalonyx, which Leidy 29 has described 
as follows: "The second upper molar in section (PI. XVI, Fig. 9, d), 
is quadrate with rounded angles. Its inner and posterior sides are the 
greater, and are nearly equal; and the remaining sides are also nearly 
equal, and are planes. The inner side is slightly convex, and the 
posterior side is nearly a plane and is directed obliquely outward." 
On the occlusal surface the transverse valley between the anterior and 
posterior crests opens most broadly on the inner side in no. 208. In 
no. 313, on the other hand, where the transverse crests are parallel, the 
valley is of nearly the same width throughout. 

M- and M- are very similar in general shape. M- may be slightly 
larger than M-, but the corresponding measurements of these teeth 
are usually very close. In the greater number of species of Hapalops, 
MA is the largest of the molariform series, and this is true in general 
for the Santa Cruz Megalonychidae. In both teeth the anterior face 
is broadly convex and the posterior face concave. The anterior face 
rounds gradually to the external side ; in other words, does not form 
a distinct angle with the outer side as in other cheek-teeth. The teeth 
do not narrow as much externally as in Megalonyx jeffersoni, in which 
respect they are more like M. leidyi. They lack the typical quadrate 
cross-section characteristic of the corresponding teeth of Megatherium. 
In M- and M- the anterior crest of the occlusal surface is decidedly 
beveled in front, and the cutting edge of this chiseled surface is usually 
worn into a crescent. The transverse valley is worn most broadly on 
the inner side. In both teeth the postero-internal angle of the occlusal 
surface is subjected to greatest wear. In several loose teeth of Nothro- 
therium from the asphalt beds, referable to M- or M-, the outer face 
is seen to be noticeably concave in its longitudinal extent. This char- 
acter apparently distinguishes these teeth from M3 and especially 
from Mg. 

M- resembles in its anteroposterior compression the corresponding 
tooth in Hapalops and in Megalonyx. It is approximately only one- 
half as long in that direction as the remaining superior cheek-teeth of 
Nothrotherium. The posterior face of M- in the species from the asphalt 
beds is very broadly concave and the concavity may become quite deep 
as in a young individual, no. 640. The nearly flat anterior face, which 
is of less width than the posterior face, may have a median strip 
defined by a slight groove on each side. The inner face may have a 
faint vertical groove near the anterior border, while the outer face is 



2n Leidy, J., op. ext., p. 17. 



154 



University of California Publications in Geology [ VoL - 10 



characterized by a well-marked median groove. On the occlusal surface 
there is no distinct valley formed, but the anterior edge is worn much 
lower than the posterior. This tooth differs decidedly from M- in 
Me gal onyx jeffersoni, which Leidy 30 describes as follows: "The last 
molar is a smaller tooth than the preceding pair, but has nearly the 
same form in a reversed position, the base of the triangular section 
( PI. XVI, Pig. 9, a) being outward. Its posterior side is transverse 
and is slightly concave; and the anterior side is convex and directed 
obliquely inward. 

Inferior series. — With the loss of the first tooth in N othrotherium 
the superior surface of the ramus directly in front of M 5 is triangular 
in shape. The tooth-rows are relatively as far separated as in Hapalops 
longiceps. They are very nearly parallel or diverge slightly pos- 
teriorly. In the Pleistocene genus the characteristic features of the 
three posterior teeth in Hapalops have been accentuated. Scott 



Fig. 8. N othrotherium shastense Sinclair. Right, inferior, dental series no. 
16fi M. H. S. A., occlusal view, natural size. First tooth to the right is M;. 
Rancho La Brea Beds, California. 

describes these teeth in H. longiceps as follows: ". . . 5 and 5 are 
transverse and rectangular, and their raised margins are quite deeply 
notched on the inner and outer sides by the transverse valley ; 5 is 
subcylindrical, as in most of the other species." 31 

In Mo and M T{ the denser, outer layer of dentine of the tooth crown 
is least developed along the outer and inner sides. It is perhaps less 
developed on the outer than on the inner side. The layer is thicker 
on the anterior and posterior faces of the crown, and appears slightly 
better developed on the posterior face. The thickness of this more 
compact layer of dentine determines in part the structure of the 
occlusal surface. The outer and inner walls which are thinnest, resist 
wear less, and are worn down more rapidly than the anterior and 
posterior walls. The latter are therefore prominent on the wearing 

' so Leidy, J., op. cit., p. 18. 
3i Scott, W. B., op. cit., p. 182, 1903. 




1917] 



Stock: Skull and Dentition of Nothrotherium 



155 



surface as two transverse ridges with intervening valley excavated in 
the softer inner material of the crown. The type of wearing surface 
thus obtained resembles very much that in the larger teeth of Mega- 
therium, but in that genus the outer compact dentine is thinner and 
the cement (on the anterior and posterior faces) relatively much 
thicker. In the Rancho La Brea Nothrotherium the cement is more 
evenly distributed on the crowns of the teeth, with a moderate increase 
on the anterior and posterior faces in some specimens. In Megatherium 
there is an excessive thickening of the cement on the anterior and 
posterior faces. 

The complete length of the crowns of Mg, Mg and M 5 is exposed 
in the somewhat broken specimen, no. 418. The teeth are seen to 
reach the inferior wall of the ramus, which is very thin. In this 
ramus the inferior teeth diverge upward in their course from the base 
to the alveolar border. In longitudinal extent the crown of is 
slightly concave posteriorly ; M s is practically straight posteriorly but 
slightly concave laterally ; M 2 evidently sloped posteriorly. M 5 and 
especially exhibit then a different longitudinal curvature from that 
shown by the third and fourth superior teeth. 

In (fig. 8) the transverse width of the anterior half is distinctly 
less than that of the posterior half. The transverse axis of the tooth 
is oblique to the long axis of the tooth-row. This tooth differs from 
the corresponding one in Hapalops and Megalonyx in the presence of 
median vertical grooves on the inner and outer faces. The anterior 
face is broadly concave while the posterior face is correspondingly 
convex. On the occlusal surface the anterior transverse ridge is nearly 
straight and may be beveled in front, while the posterior is crescentic 
and is beveled behind. 

is slightly larger than and narrows more toward the inner 
side. It is transversely placed with reference to the long axis of the 
tooth-row. In occlusal view it resembles somewhat the third and fourth 
superior teeth, but is in reverse position. If the tooth is oriented so 
that the posterior margin of the occlusal surface corresponds to the 
anterior margin of the third or fourth superior tooth, the former can 
be distinguished by rounding less gradually toward the narrow lateral 
side. In other words, the third inferior tooth has all four angles better 
defined than those in the third and fourth superior teeth. This serves 
also to distinguish M2 from either M- or M-. The vertical grooves of 
the lateral faces appear, as a rule, to be more sharply defined than in 
Mtj, while the anterior half of the tooth is not as distinctly smaller 



156 



University of California Publications in Geology [Vol. 10 



No.456 

59 


No.418 
51.7 


No. 637 
49.4 


No.63E 
48.5 


13.6 


13.9 


ol2.5 


all.8 


17.6 


15.9 


al6.3 


al6.2 


14.1 


al4.7 


13.3 


13.4 


18.4 


16 


16.4 


16.4 


13.4 




14.5 


al5 


16.2 




15 


14.8 



transversely as the posterior half. M 5 differs from the corresponding 

tooth of Hapalops and Mcgalonyx in the presence of well-marked 
lateral grooves. The anterior and posterior faces resemble those in M 5 . 

<j <i <i <i < <j << <j <j 

cog cog cog cog oi* ajg cog cog cog 

Measurements of Km Km Km Mm Kn Kb Km Km 

Dentition |gj gg« ggj ggj ggj |g« »gj |g« »g« 

to o % <*> o ^ o « o "Sn o "S^o "£ d o « o o « H o 

rt^jjz: c; °~ cis c3«^ a co & c3^x! 

BQ . f5 ta • fi co.Cl to.d to.fl eo . Pi co. PI ta.eJ cg . S 

, o d , O s . O cj .On! . O cfi . O C3 . O c3 . O c3 . O e3 

ZZK 5?S?P3 g£« fcfcK ZZK 

Greatest length of su- 
perior molar series, 

alveolar measurement 61.6 mm. 62.8 61.5 57.5 62.3 65.4 

M 5 , greatest anteropos- 
terior diameter 12 12 12.1 al2.3 12.4 10.4 9.7 9.9 

M-, greatest transverse 

diameter 12.9 13 13 al3.7 14.3 10.5 11.2 11.9 

M 3 , greatest anteropos- 
terior diameter 13.3 13 ol4 13.8 11 

M 2 , greatest transverse 

diameter 16.8 16.9 al6.8 18.9 14.4 

M>, greatest anteropos- 
terior diameter 13.2 13 12.8 13 12.1 11.2 10.8 

M 1 , greatest transverse 

diameter 17 17.2 17 17 18.3 14.4 13.5 

M 5 , greatest anteropos- 
terior diameter 8.7 7.6 7.3 «7.8 8.8 7.3 7.2 7.5 

M-, greatest transverse 

diameter 13.6 14.4 13.8 al2.9 16 11.5 10.5 11.3 

Greatest length of in- 
ferior molar series, No. 636'* 
alveolar measurement 57 54.7 51.7 

M.2, greatest anteropos- 
terior diameter 13.6 

Mi, greatest transverse 

diameter 16.5 

M5, greatest anteropos- 
terior diameter 14.2 13.5 

M5, greatest transverse 

diameter 17 17.5 

Mj, greatest anteropos- 
terior diameter 14 15 14 

Mj, greatest transverse 

diameter 15.6 15.8 15 



* This specimen may belong to cranium 313. 
», approximate. 



The single tooth, no. 10495 Univ. Calif. Coll. Palae., of Nothro- 
therium previously described by the writer from Rancho La Brea, was 
assigned to the superior dentition chiefly on similarity of its cross- 
section to that of the second alveolus. It was remarked, however, that 
the Rancho La Brea specimen differed from no. 8702 from Potter 



1917] Stock: Skull and Dentition of Nothrotherium 157 



Creek Cave in longitudinal curvature. The longitudinally concave, 
posterior face of no. 10495 and the distinctness of the angles of the 
occlusal surface relate this specimen much more closely with the 
second inferior tooth than with either the third or fourth superior 
teeth. The occlusal surface resembles also that of Mg. No. 10495 is 
then either a second or third inferior tooth. 

The last inferior tooth, which in Hapalops is more or less cylin- 
drical in shape, retains the rounded internal side in Nothrotherium. 
It thus agrees with Megalonyx in differing markedly in shape from 
either M 3 or M^. This tooth in Megatherium, although smaller and 
relatively longer anteroposteriorly than and M3-, is essentially of 
the same shape as the other inferior teeth. The transverse axis 
of M 5 in Nothrotherium is directed obliquely to the long axis of the 
tooth-row, thus resembling Hapalops and Megalony.r. On the outer 
flattened face of this tooth a median vertical groove may be slightly 
defined as in no. 208, or well defined as in no. 456. In the presence 
of this groove, Nothrotherium differs from Hapalops and Megalonyx. 
The outer anterior and posterior corners of are well rounded. The 
denser layer of dentine is best developed on the inner and posterior 
sides and least on the outer side. The border of the occlusal surface 
is least worn at the middle of the inner side and at the postero- 
external corner. Between the resulting prominences, the border is 
beveled posteriorly. In Megalonyx the occlusal surface of the corre- 
sponding tooth is somewhat similarly worn. It is described by Leidy 
as having "... a transverse valley, whose boundaries are most 
prominent at the antero-internal and postero-external angles." 32 

EE VIEW OF SPECIES 
In a former note 33 the writer briefly described a single skull of 
Nothrotherium without mandible from Rancho La Brea, which was 
referred to a new species, N. graciliceps. At that time the only other 
material of this genus available from the asphalt was a single tooth, 
no. 10435, in the palaeontological collections of the University of 
California. In a comparison of the Rancho La Brea N othrotherium 
with N . shastense from Potter Creek Cave, it was inferred that the 
lower jaw in the former species was longer than in the latter. The 
principal difference, however, between the two forms was thought to 
rest in the shape of the last superior tooth. 

32 Leidy, J., op. cit., p. ] 9. 

-"■Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 341-358, 1913. 



158 



University of California Publications in Geology [Vol. 10 



In addition to the skull material contained in the collections of the 
Museum of History, Science and Art of Los Angeles, there are also 
available for comparison five mandibles as well as fragments of 
mandibles of Nothrotherium from the asphalt beds. These specimens 
show a considerable range in size. No. 636 represents one of the 
smaller individuals and approximates very closely in size the frag- 
mentary ramus, no. 8-122 Univ. Calif. Coll. Palae., from Potter Creek 
Cave. The latter if anything is slightly smaller than no. 636. The 
differences between the specimens are slight. The tooth-row in no. 
8122 is a trifle longer; the postero-external opening of the dental 
canal is small and the ascending portion of the ramus behind Mj is 
apparently a little thicker than in no. 636. On the whole the char- 
acters presented by the fragmentary ramus from Potter Creek Cave 
are hardly to be distinguished from those of the Rancho La Brea 
specimens. 

Associated with the ramus of N. sliastense from Potter Creek Cave 
are a number of teeth, one of which Sinclair 34 identified as a last 
superior tooth. He describes this specimen as follows: "It is a tri- 
angular tooth with the posterior side plane, the anterior convex, and 
the outer plane and meeting the posterior at a right angle." 35 A com- 
parison of this tooth with the last superior alveolus of skull 15 from 
Rancho La Brea showed that the latter must have possessed a M 5 
which differed markedly from Sinclair's specimen. This has been 
amply verified by the additional material now available. The shape 
of the tooth in the species from the asphalt beds is remarkably con- 
stant. It differs from the corresponding tooth, no. 8497 Univ. Calif. 
Coll. Palae.. from Potter Creek Cave in (1) subtrapezoidal outline. 
(2) outer and inner sides of equal thickness. (3) posterior face con- 
cave transversely, (4) presence of vertical groove on outer face and 
faint vertical groove on inner face near anterior border, and (5) outer 
and anterior faces concave longitudinally. 

The differences noted are undoubtedly great enough to separate 
the Rancho La Brea form as a distinct species, if Sinclair's specimen 
can be regarded with certainty as a last superior tooth of Notliro- 
therium. A critical re-examination of this tooth has convinced the 
writer that there are, however, serious objections to its being considered 
as such. As stated by Sinclair, no. 8497 (fig. 9) has been somewhat 

34 Sinclair, W. J., New mammalia from the quaternary eaves of California, 
Univ. Calif. Publ. Bull. Dept. Geol., vol. 4, pi. 23, fig. 8, 1905. 

35 Sinclair, W. J., ibid., p. 154. 



1917] 



Stock: Skull and Dentition of Nothrotherium 



159 



injured by rodents, especially toward the occlusal surface. The 
gnawed surfaces of the tooth do not seem to account entirely for the 
difference in size of the two ends : that is to say, the tooth narrows 
toward the occlusal face. This is considered as characteristic of 
immature individuals. It is apparent also that this tooth is excep- 
tionally large in comparison with the remaining teeth of Nothrotherium 
shastense. Furthermore, there are several teeth in the collections from 
Potter Creek Cave which are not clearly referable to Nothrotherium, 
but belong perhaps to a small species of Megalonyx. In fact, Sinclair 
described a specimen, no. 820H, from the cave deposit which he 
identified tentatively as belonging to Megalonyx wheatleyi. With the 
fifth superior tooth of M. jeffersoni no. 8497 from Potter Creek Cave 
agrees in triangular shape but differs in size. The latter specimen 



LP 

Fig. 9. Megalonyx(?), sp. M-, no. 8497, Univ. Calif. Coll. Paine., anterior 
view with outline of section through pulp-cavity, natural size. Potter Creek 
Cave, Shasta County, California. 

lacks possibly "the slightly concave" posterior face noted by Leidy 
in M. jeffersoni, but this can only be regarded as a minor difference. 

In a former note the writer considered specimen 8337 from Potter 
Creek Cave as probably representing an inferior tooth. The characters 
• seen in occlusal view relate this specimen much more closely with M 5 
and Mg than with M- or M-. The concave posterior face in its longi- 
tudinal extent is a character held in common by no. 8337 and of 
Nothrotherium from Rancho La Brea. The tooth from Potter Creek 
Cave differs slightly from the second and third inferior teeth from 
the asphalt beds in having the four angles of the occlusal surface 
slightly more sharply defined. 

While the comparatively large size of no. 845)7 is in itself not 
sufficient reason for generic determination as other than Nothro- 
therium, in view also of its much closer resemblance to the fifth 
superior tooth of Megalonyx the identification with the latter is more 
probable than with Nothrotherium shastense. The fragmentary 




160 University of California Publications in Geology [Vol. 10 



ramus, no. 8422. from Potter Creek Cave, presents but insignificant 
differences when contrasted with specimens from Rancho La Brea. 
In addition to no. 8497, a number of upper and lower teeth were 
regarded by Sinclair as pertaining to N. shastense. These specimens 
resemble closely in size and shape corresponding teeth of the Rancho 
La Brea species. Unless other characters favoring a specific separation 
of the Rancho La Brea material are revealed, N. graciliceps must be 
regarded therefore as synonymous with N. shastense. 

Dr. 0. P. Hay 36 has recently described as a new species, Noth.ro- 
therium texanum, a damaged skull possessing the superior dental series 
of one side but lacking the lower jaw. The specimen is reported to 
have come from northern Texas, presumably from Pleistocene deposits. 

As indicated by Dr. Hay comparison between the Texas species and 
N. shastense from Potter Creek Cave is restricted to loose teeth found 
with the type ramus of the latter species. Of these, he considers speci- 
mens figured by Sinclair 37 as representing the second and third teeth. 
Specimen 8702 from Potter Creek Cave, represented in figures 3 and 
3a of Sinclair's paper agrees very closely in size with the second 
superior tooth of N. texanum. Dr. Hay believes that the teeth of 
A r . texanum can be distinguished, for in no. 8702 "both the front and 
the rear faces are convex in section, whereas both the second and the 
third teeth of N. texanum have the front face convex and the rear face 
concave." 38 In no. 8702 from Potter Creek Cave the posterior face 
is not entirely convex, for as is shown in section there is developed 
toward the outer side a slight but nevertheless distinct concavity. 
Furthermore, in teeth from Potter Creek Cave, representing either 
M- or M- of the superior dental series, the depth of this concavity 
may vary greatly. 

Tooth 8337 from Potter Creek Cave, represented in figures 5 and 5a 
of Sinclair's paper, is regarded by Hay as being the third (M-) of 
the superior series. In the previous note on the Rancho La Brea 
Not It roth erium. the writer stated that no. 8337 is probably of the 
inferior dentition, a view which is still maintained. 39 

Hay, O. P., Descriptions of two extinct mammals of the Order Xenartbra 
from the Pleistocene of Texas, Proc. U. S. Nat. Mus., vol. 51, pp. 107-123, pis. 
3-7, 1916. 

37 Sinclair, W. J., New mammalia from the quaternary caves of California, 
Univ. Calif. Publ. Bull. Dept. Geol., vol. 4, pi. 23, figs. 3, 3a, and 5, 5a, 1905. 

38 Hay, O. P., ibid., p. 121, 1916. In the present paper the superior teeth of 
N 'othrotherium regarded by Hay as second and third have been designated M- 
and M 1 respectively. 

39 Vide supra, p. 159. 



1917] 



Stock: Skull and Dentition of Nothrotherium 



161 



The fifth superior tooth, no. 8497, from Potter Creek Cave, re- 
ferred to Nothrotherium by Sinclair, has been shown above to resemble 
Megalonyx much more closely. It undoubtedly does not pertain to 
the former genus. The characteristic features exhibited by this speci- 
men cannot then be used as distinguishing Nothrotherium shastensc. 

It is evident from the above discussion that it is not possible to 
separate N. texanum from N. shastcnse on the basis of characters at 
present available. 

Dr. Hay considers the Texas form as very closely related to the 
Rancho La Brea species of Nothrotherium, as indicated by a com- 
parison with skull 15 contained in the collections of the Museum of 
History, Science and Art of Los Angeles and described by the writer 
in 1913. He remarks, however, that "One can not rely wholly on the 
differences which are seen in the two skulls for additional specimens 
may be intermediate. ' ' 4 " The characters exhibited by the teeth of 
N. texanum fall easily within the range of variation of teeth in Rancho 
La Brea skulls. One of the important skull characters cited by Hay as 
distinctive of N. texanum is the structure of the pterygoid bulla. In 
the Texas specimen the bulla of each side is open wide below, in which 
respect it is in marked contrast to that of Rancho La Brea skulls. 
In the latter the pterygoid bullae when undamaged are always com- 
pletely closed below with the exception of an elongate orifice on the 
inner ventral side. The pterygoid bulla in the skull of Nothrotherium 
from Brazil, described by Reinhardt, lacks even this internal opening 
and is apparently complete. 

Judging from the damaged condition of the skull of N. texanum 
(the palate being severely injured and the pterygoid plates entirely 
broken away in that specimen), such fragile structures as the ptery- 
goid bullae can hardly be expected to remain entire. It is then reason- 
able to snppose that the present appearance of these bullae in the Texas 
specimen is to be attributed to injury sustained during preservation. 
Dr. Hay is, however, of the opinion that the pterygoid bulla in A. 
texanum remained widely open below during the life of the indi- 
vidual. He states: "The bulla of N. texanum appears not to have 
had a floor. The pterygoids seem to form a wall which surrounds the 
cavity on both sides. On the median side the edge of the wall is 
partly intact, partly injured. On the outer side the wall comes 
down to a sharp thin edge which appears to be little if at all injured. 
In places the edge is certainly wholly natural. Such being the case 

40 Hay, O. P., ibid., p. 121, 1916. 



162 University of California Publications in Geology [Vol. 10 



the bulla is incomplete and is a cavity opening below by a mouth 
30 mm. wide. ' ' 41 

Of other skull characters considered by Hay as distinctive of A 7 . 
texanum mention may be made of the dorso-ventral diameter or height 
of muzzle and combined width of the nasals. In contrast to no. 15 
additional skulls now contained in the collections of the Museum of 
History, Science and Art of Los Angeles approach the Texas specimen 
much more closely in height of muzzle. This is particularly true of 
no. 166 in which the height is 49.2 mm. The combined width of the 
nasals in the latter skull corresponds almost exactly with that in 
A 7 , texanum. 

EELATIONSHIPS OF GENUS 

In this paper it is proposed only to touch upon some of the most 
significant relationships of N othrotherium as brought out in a study 
of the skull and dentition. The skeletal elements, associated with the 
skull material in the Museum of History, Science and Art of Los 
Angeles, furnish also a wealth of evidence concerning relation to 
Miocene and Pleistocene ground-sloths, and until the whole skeleton 
can be fully studied it is perhaps premature to enter on a final con- 
sideration of the systematic position of the genus. 

The many resemblances between N othrotherium and Hapalops, as 
shown by the foregoing comparisons, strongly support the view that 
the former genus is derived from Hapalops as held by Scott. More 
recently F. Ameghino 4 - in a discussion of the Miocene relatives of 
N othrotherium derives the genus from a Hapalops-like form. It is 
not clear which genus he considers closest in this Miocene ancestral 
relationship, 43 for in one phyletic scheme he derives A 'othrotherium 
from Trematherium while in another he considers the genus as descend- 
ing from Xyophorus. According to Scott, Trematherium is very 
imperfectly known, while Xyophorus is synonymous with Hapalops. 

As already noted, the type of skull characteristic of N othrotherium 
has deviated less from the more generalized type of the Miocene 
Megalonychidae than has Megalonyx. The differences between 
N othrotherium. and Megalonyx, which in many respects make them 

4i Hay, O. P., ibid., p. 119, 1916. 

4- Ameghino, F., Notas sobre una pequeria coleccion de huesos de mamiferos 
proeedentes de las grutas calcareas de Iporanga en el Estado de Sao Paulo- 
Brazil, Eevista do Museu Paulista, vol. 7, pp. 99-119, 1907. 

*s Ameghino, F., ibid., pp. 105 and 119. 



1917 | 



Stock: Skull and Dentition of Nothratherium 



163 



very dissimilar in structure of skull, are to be considered as end- 
products of two widely divergent lines of evolution arising from more 
closely related forms in the Tertiary. The writer is thus entirely in 
accord with Scott, who states with reference to the Santa Cruz ground- 
sloths : ' ' That Hapalops is nearly related to both Nothrotherium arid 
Megalonyx is abundantly clear from a cursory examination of the 
skeleton, all parts of which are very similar to those of the two 
Pleistocene genera. In fact, there is every reason to believe that 
Nothrotherium was the direct descendant of some species of this 
genus. ' Hi 

With a reduced dentition. Nothrotherium is not only more special- 
ized than Hapalops, but is also more advanced than either Megalonyx or 
Megatherium. In a comparison of the two Pleistocene megalonychids, 
Ameghino states: "Pero en cambio. Megalonyx que tiene cinco dientes 
en cada lado aparece como una forma considerablemente mas primitiva 
que Nothrotherium que solo tiene cuatro. ' Hs Judging from the struc- 
ture of the skull, the position of the molariform teeth in Nothrotherium 
undoubtedly corresponds to that of the four posterior teeth of 
Megalonyx. Thus a closer relationship between these genera than 
between Nothrotherium and Megatherium is indicated by the position 
of the molariform teeth. This resemblance extends also to the shape 
of these teeth. 

In Notltrotherium and Megalonyx M- is smaller than M- or M- and 
this is usually true also for Hapalops; M- as a rule can be distinguished 
from M± by its slightly larger size; M- is compressed anteroposterior^'. 
In the inferior molariform series the principal character held in 
common (with slight modifications) by the three geriera is the shape 
and position of M 5 . In Hapalops this tooth is sub-cylindrical, while 
in Nothrotherium and Megaton yx it has essentially the same shape but 
with the outer side flattened. Further, in the three genera the trans- 
verse axis of M ; is somewhat oblique to the long axis of the tooth-row. 
In Megatherium this tooth is quadrate in shape, and transverse in 
position, thus resembling the remaining inferior teeth. 

CONCLUSIONS 

Next to Mylodou, the genus Nothrotherium is the most abundant 
ground-sloth found at Rancho La Brea. It is represented by decidedly 
fewer individuals than is Mylodou. The occurrence of Nothrotherium 



** Scott, W. B., op cit., p. 181, 1903. 
> r > Ameghino, F., op. cit., p. 103. 



164 University of California Publications in Geology [Vol. 10 



in the asphalt beds in greater numbers than Megalonyx is singular, 
considering the apparently more restricted range of the former genus 
in North America. There is reason for believing, however, that 
Nothrotherium nourished in California and Texas during a portion 
of the Pleistocene. 

The species of Nothrotherium from the asphalt beds, originally 
considered by the writer as new, is now held to be identical with N. 
shastense Sinclair from Potter Creek Cave. Further investigation 
may justify a subspecific separation of the Rancho La Brea form, but 
at present there is not sufficient reason for a specific distinction from 
the Potter Creek Cave species. 

The many characters held in common by A r . texanum and N. 
shastense from Potter Creek Cave and Rancho La Brea suggest specific 
identity of the two forms. 

Nothrotherium is very closely related to the Miocene genus 
Hapalops. Comparison between the two genera presents nothing 
which can be considered adverse to the view held by Scott, that 
Nothrotherium is the direct descendant from Hapalops. The Pleisto- 
cene genus shows several noticeable advances beyond the Miocene 
form in skull and dentition. The structure of the skull in Nothro- 
therium indicates a type which has deviated less than Megalonyx 
from a generalized skull characteristic of the Santa Cruz ground-sloths. 

The great dissimilarity between Nothrotherium and Megalonyx in 
many characters of skull and dentition substantiates the views of Scott 
and Ameghino that these genera are the results of two divergent lines 
of evolution already separate in the Santa Cruz Miocene. The differ- 
ences between the two Pleistocene genera are in many instances so 
great as to suggest a separation of subfamilies rather than genera. A 
close resemblance between the two forms is shown by the position and 
general shape of the molariform teeth, in which characters both genera 
are more closely related to each other than either is to Megatherium. 



Transmitted June 16, 1916. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 11, pp. 165-178, plates 3-4 Issued April 17, 1917 



FURTHER OBSERVATIONS ON THE SKULL 
STRUCTURE OF MYLODONT SLOTHS 
FROM RANCHO LA BREA 



BY 

CHESTER STOCK 



UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 11, pp. 165-178, plates 3-4 Issued April 17, 1917 



FURTHER OBSERVATIONS ON THE SKULL 
STRUCTURE OF MYLODONT SLOTHS 
FROM RANCHO LA BREA 

BY 

CHESTER STOCK 



CONTENTS 

PAGE 



Introduction 165 

Cranium , 16G 

Mandible 168 

Dentition 168 

Mylodon harlani tenuiceps, n. subsp 171 

Conclusions 174 



INTRODUCTION 

Opportunity has recently been afforded the writer to examine 
the very extensive series of mylodont skulls from Rancho La Brea 
contained in the collections of the Museum of History, Science and 
Art of Los Angeles. This series consists of thirty-two crania and a 
number of mandibles, for the most part well preserved, together with 
other skull material not in as favorable a state of preservation. The 
splendid collection at the Museum in Los Angeles rivals in wealth of 
material the great collections of Pampean ground-sloths in South 
American museums. 

In examination of the Los Angeles series of skulls a number of 
interesting points presented themselves which were not touched upon, 
or were but little discussed, in the preliminary report by the writer 1 
on the University of California series. Several of the skulls examined 
were found to differ in certain features from the broad type character- 

1 Stock, C, Skull and dentition of the mylodont sloths of Rancho La Brea, 
Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, pp. 319-334, 1914. 



166 University of California Publications in Geology [Vol. 10 

istie of Mylodon harlani from Rancho La Brea, and as these characters 
are apparently constant and cannot be satisfactorily shown to grade 
into the usual type of skull from the asphalt deposits, they are con- 
sidered to represent a new subspecies. It may be possible to establish 
a series with uniform and perfect gradations between the narrow 
and broad types of skulls of M. harlani when the entire mylodont 
sloth collection is reviewed, but at present it seems necessary to make 
the distinction between the two forms. 

I desire to acknowledge my thanks to Mr. Frank S. Daggett, Direc- 
tor of the Museum of History, Science and Art of Los Angeles, who 
not only very kindly allowed me to examine the ground-sloth material 
but rendered many personal favors during my stay at the Museum. 
I desire also to thank the other members of the staff for many cour- 
tesies shown me. The photographs of the skull of the new subspecies 
were taken at the Museum by Mr. L. E. Wyman. 

CEANIUM 

Of the thirty-two skulls of mylodont sloths contained in the Rancho 
La Brea collections of the Los Angeles Museum of History, Science 
and Art, by far the greater number range approximately between 
460 mm. and 525 mm. in length (from anterior end of maxillary to 
posterior end of occipital condyles). None of the skulls attain the 
length of the Colorado specimen described by Professor Coekerell. 2 
With the exception of three, possibly four crania, this series is com- 
posed of skulls having the general characteristics already discussed in 
connection with a similar series contained in the palaeontological 
collections of the University of California. 

Specimens 642, 643, 646, and 695 3 differ from the usual broad type 
of skull of Mylodon harlani from Rancho La Brea in the decidedly 
more slender cranium posterior to the postorbital processes. For skull 
642 this is distinctly indicated in plate 3. In this respect they ap- 
proach more closely the skull-form in Mylodon garmani, differing, 
however, in being much less slender. With the least width of the 
skull behind the postorbital processes as a convenient and suitable 
index of slenderness of the cranial case, a series can be established 
with gradations tending toward the broader type of skull. The speci- 

- Coekerell, T. D. A., A fossil ground-sloth in Colorado, Univ. Colo. Studies, 
vol. 6, pp. 309-312, 2 pis., 1909. 

s All numbers used in this paper, unless otherwise stated, are the catalogue 
numbers of specimens contained in the Rancho La Brea collections of the Museum 
of History, Science and Art of Los Angeles. 



1917] 



Stock: Skull Structure of Mylodont Sloths 



167 



men showing the greatest constriction is no. 646, while nos. 642, 643, 
and 695 show successively less constriction. The Nebraska skull de- 
scribed by Barnum Brown 4 is slightly more constricted than no. 646, 
but the actual difference is so small that it is negligible. In this 
arrangement, the skulls, including the Nebraska specimen, exhibit a 
variation in length of approximately only 30 mm. 

In a former paper the writer 5 stated that the inflation of the 
muzzle in the mylodont skulls of the University of California series 
was similar to that in the Nebraska skull. This is true also for the 
greater number of skulls contained in the Museum of History, Science 
and Art of Los Angeles, as far as the actual diameter of muzzle is 
concerned. In proportion to the postorbital constriction, however, 
many of the skulls, including the slender types, are slightly less 
inflated at the muzzle than Brown's specimen. 

The palate posterior to the fifth superior tooth is very narrow in 
the slender type of skull from Ranch o La Brea. This character 
apparently does not depend on the slenderness of the cranium, since 
in M. garmani the palatal index is actually greater than in a broad 
skull of M. harlani (no. 21158 Univ. Calif. Coll. Palae.) of approx- 
imately the same length. Furthermore, in no. 21160 Univ. Calif. Coll. 
Palae., a narrow palate, which is 57.5 mm. in width, is associated with 
a broad cranium. The slender skulls again lend themselves to a 
gradational arrangement, which, however, is not the same as for the 
cranial index. No. 642 possesses the least width of palate posterior to 
the fifth tooth, the transverse diameter gradually increasing in skulls 
646 and 643. The Nebraska skull in this character follows no. 643. 

In none of the skulls contained in the Museum of History, Science 
and Art is the fifth superior tooth as little removed from the middle 
of the postpalatine notch as in Brown's specimen, or as far removed 
as in the skull described by Cockerel! 

The flattened dorsal surface of the brain-case, outlined by the 
occipital crests, varies in width irrespective of the degree of slender- 
ness of the cranium. In the slender skulls the width of this sur- 
face may be equal to or greater than in some of the broader types. 
In skull 707 the dorsal surface of the cranium is very wide, thus differ- 
ing from the remaining skulls from the asphalt beds and resembling 
closely Mylodon robustus as figured by Owen. 6 

* Brown, B., Bull. Amer. Mus. Nat. Hist., vol. 19, pp. 569-583, pis. 50-51, 1903. 
s Science, n.s., vol. 39, pp. 761-763, 1914. 

Owen, B., Description of the skeleton of an extinct gigantic sloth, etc. 
(London, 1842), pi. 3. 



168 University of California Publications in Geology [Vol. 10 



MANDIBLE 

A number of mandibles together with separate rami, some of which 
are directly associated with crania, are also in the collections of 
the Museum of History, Science and Art. These exhibit the degree 
of variation already discussed in connection with the University of 
California series of lower jaws. 

In general the ramus decreases noticeably in height from the base 
of the coronoid process to the anterior side of the first lower tooth. 
Occasionally, as in no. 696, the height of the ramus in front of the first 
tooth is much greater, and resembles M. garmani and 31. robustus as 
well as no. 21576 Univ. Calif. Coll. Palae. In no. 696, also, the inferior 
dental canal of the right ramus opens anteriorly by three foramina. 
The latter variation from the normal number of two occurs quite 
frequently, much more so than the occurrence of only a single open- 
ing. The greatest predental width of the mandible is always less 
than the distance between the first tooth of each side. 

Unfortunately there are do mandibles directly associated with the 
three exceptionally slender skulls. An incomplete and badly worn 
mandible, showing the complete lower dentition on one side is, how- 
ever, associated with no. 695. This specimen exhibits a remarkable 
abnormality in the presence, anterior to the first inferior tooth, of a 
distinct alveolus for an extra tooth. It is present only on the right 
ramus, where it is 9 mm. in advance of the normally placed first tooth. 
The alveolus measures 11 mm. in anteroposterior diameter by approx- 
imately 9 mm. transversely. 

DENTITION 

The thirty-two skulls contained in the Museum of History, Science 
and Art of Los Angeles exhibit a variation in the superior dentition 
similar to that noted in the University of California series, namely : 

1. Skulls with four teeth on each side of the palate. 

2. Skulls with four teeth on one side of the palate and five teeth 
on the opposite side. 

3. Skulls with five teeth on each side of the palate. 

The three, possibly four, slender skulls show the following vari- 
ation : nos. 646 and 643 possess the normal number of five functional 
teeth on each side of the palate, no. 695 is an example of the second 
group, in which there are five teeth on one side and only four on the 
opposite side of the palate, and no. 642 had only four functional teeth 
on each side of the palate. 



1917] 



Stock: Skull Structure of Mylodont Sloths 



169 



This splendid series of specimens receives added importance in 
that it demonstrates completely how the first tooth of the superior 
series may disappear. In skull 694, a specimen originally of the third 
group, the alveolus for the first tooth is very well developed. On 
the left side of the palate the first alveolus was originally as well 
developed as on the right side. Around the border of the former 
alveolus an irregular, spongy growth of bone is formed which shows 
a tendency to grow toward the middle of the tooth-socket. That this 
actually takes place is well exhibited by no. 642, in which the closure 
of the first superior alveoli has progressed much further. In this 
skull the first alveolus of the left side is almost completely closed, 
while that on the right side has a shallow, crescentic opening along its 
lingual border. 

No. 693 illustrates how the entire alveolus may be filled by a 
spongy growth of bone. The final stage is reached in no. 21156, Univ. 
Calif. Coll. Palae., for example, or in the Nebraska skull described by 
Brown, where the first superior tooth has entirely disappeared, its 
former presence being indicated by a scar in front of the second 
superior tooth. 

It is interesting to note in this connection that somewhat similar 
observations on the closure of the first superior alveoli in South 
American mylodonts have been made by Burmeister, 7 who states : 

. . . Der Schadel des hiesigen Museums [a skull referred to Grypotherium and 
contained in the collections of the Museo Nacional at Buenos Aires] hat noch 
offene Alveolen im Oberkiefer; in dem von Reinhardt abgebildeten Schadel sind 
sie schon ganz mit Knochenmasse gefiillt, aber als Narben sichtbar geblieben. 

AVhatever the initial cause of the disappearance of the first 
superior tooth may have been, it is certain that in some cases the 
tooth was well developed at the time of its disappearance. It is 
conceivable that the tooth may have broken off during the life of the 
individual, an accident which might readily have occurred, consider- 
ing the habits of the animal. A rapid growth of bone around the 
periphery of the alveolus may perhaps have prevented the tooth again 
becoming functional, and as a result resorption took place. It does 
not seem probable that such resorption was due to old age alone, 
although this may also have been a factor. In other skulls variation 
in size of the first tooth favors the idea that growth may in some indi- 
viduals have been inhibited from the start. In no. 21158 Univ. Calif. 



i Burmeister, H., S.-B. Akad. Berlin, p. 1132, 1886. 



170 University of California Publications in Geology [Vol. 10 

Coll. Palae., for example, the first tooth, present only on the right 
side, was very diminutive. It is therefore not improbable that in some 
skulls the development of the first tooth may have been completely 
arrested. 

As already stated, there are no mandibles directly associated with 
nos. 642, 643, and 646. A fragmentary lower jaw does, however, 
accompany no. 695, in which the fourth lower tooth is well preserved. 
This tooth is relatively as much elongated anteroposteriorly as that 
in the Nebraska specimen. It agrees also with Brown's specimen in 
the direction of the anterior and posterior lobes with reference to the 
long axis of the tooth-row. The anterior lobe has the usual oblique 
position with reference to that axis. The posterior lobe is placed trans- 
versely to the long axis of the tooth-row, in which respect the tooth 
not only agrees with M T of the Nebraska skull, but with corresponding 
teeth belonging to broader skulls from Rancho La Brea. The isthmus 
connecting the anterior and posterior lobes is broadly convex on its 
outer side, thus differing decidedly from the Nebraska specimen, in 
which a pronounced external fold is developed. In no. 696, a skull of 
the broad type, the external fold, or middle lobe, of the fourth inferior 
tooth is much more distinctly developed than in no. 695, although 
much less so than in no. 21156 Univ. Calif. Coll. Palae. The latter 
specimen approximates most closely the type of fourth inferior tooth 
seen in the Nebraska skull. An examination of twenty or more lower 
jaws in the Museum of History, Science and Art of Los Angeles, in 
various stages of completeness, failed to reveal a fourth lower tooth 
showing exactly the same stage of development as in the Nebraska 
specimen. 

It may perhaps be urged that in no. 695 the abnormality shown 
by the presence of an extra tooth may have extended itself to the 
dentition as a whole, and thus invalidate any conclusion which may 
be drawn from a study of the fourth inferior tooth. The first inferior 
tooth in no. 695 appears to be more compressed anteroposteriorly, 
giving a subcircular rather than an oval or reniform section, which 
is the usual type in Rancho La Brea skulls. The remaining lower 
teeth show no characteristics which are not to be seen in other skulls, 
and apparently have developed normally. 

Further modifications of the fourth inferior tooth, remarkable for 
its variability, may be noted. The anterior lobe of the tooth may be 
narrow oi' broad. It may have the usual, transverse position with 
reference to the long axis of the tooth-row as in no. 696 for example, 



1917] 



Stock: Skull Structure of Mylodont Sloths 



171 



or the inner half of this lobe may be reflected anteriorly, assuming a 
position more nearly at right angles to the long axis as in no. 645. The 
posterior lobe may be at right angles to the long axis, as already noted, 
or it may also be decidedly oblique, as in no. 645. In the latter speci- 
men, which in length of skull exceeds somewhat Mylodon garmani, 
the fourth inferior tooth of the right side has practically the same 
anteroposterior length as in that species, while the tooth of the left 
side is somewhat shorter. 

The third inferior tooth may occasionally be quite broad from the 
antero-internal to the postero-external side, as in no. 696. As a rule, 
the proportions of this tooth are more like those in the type of M. 
harlani, or the tooth may be narrower in Rancho La Brea skulls. 

The fifth superior tooth generally is comparatively small. In no. 
642 the anteroposterior diameter of this tooth is somewhat longer than 
is usual, and thus is more like the corresponding tooth in Brown's 
specimen. 

MYLODON HAELANI TENUICEPS, n. subsp. 
Plates 3 and 4 

Type specimen no. 642, a skull contained in the Rancho La Brea collection of 
the Museum of History, Science and Art of Los Angeles. 

Subspecific characters. — Skull more constricted behind postorbital processes 
and cranium more slender than in M. harlani from Rancho La Brea. Associated 
with these characters is a very narrow palate posterior to the fifth tooth. In 
possessing a slender cranium the subspecies approaches M. garmani more than 
does the typical M. harlani from the asphalt deposits, differing, however, from 
both in distinctly narrower palate. It resembles the Nebraska skull, no. 2780, 
Amer. Mus. Coll., described by Brown in degree of constriction behind the post- 
orbital processes, but differs in having a narrower palate. 

The extensive range of variation exhibited by the skull and denti- 
tion of Mylodon harlani makes it difficult to establish a type absolutely 
distinct from the parent species. It does not seem possible to establish 
a series showing gradations between one extreme, as represented by 
no. 642, and the other extreme as exemplified by no. 21158 Univ. 
Calif. Coll. Palae., because of difficulties encountered in endeavoring 
to bridge the gap between the narrow and broad types of skulls. 

No. 644 was considered at, first to supply a very necessary link in 
establishing a series of nearly perfect gradation, but after further 
comparison its affinities appeared to be rather more with the broader 
skulls. In least width of palate and least width of skull behind post- 
orbital processes (see table of measurements 8 ) no. 644 is undoubtedly 

8 Compare with table of measurements in Univ. Calif. Publ., Bull. Dept. Geol., 
vol. 8, p. 326, 1914. 



172 University of California Publications in Geology [Vol. 10 

more like the broader skulls than are the three slender specimens. No. 
644 belongs apparently to a younger individual than those having the 
slender skulls, judging from the closure of the coronal and parieto- 
squamosal sutures. These sutures are hardly, if at all, discernible 
in the latter specimens. It may be possible that the sutures have 
closed for other reasons than age alone. 

An objection to the separation of a new subspecies may be raised 
by the apparent inconstancy in Mylodon harlani of the variations 
given as characteristic of M. h. tenuiceps. No. 21160 Univ. Calif. 
Coll. Palae. has been cited as an example in which a small palatal 
index is associated with a broad cranium, while in Brown's specimen 
from Nebraska a small cranial index is associated with a compara- 
tively broad palate posterior to the fifth tooth. It is also worth noting 
that in M. garmani, although the cranial index is very small, the 
palate is very broad. In establishing the subspecies the writer has 
been impressed by the lack of continuity in the gradations exhibited 
by the Rancho La Brea series when the two characters under consid- 
eration are taken in combination, rather than by the variability of 
the characters taken separately. 

The writer would not hesitate to include the Nebraska skull de- 
scribed by Brown in this subspecies, and thus render a new name 
unnecessary, were it not for the following considerations : 

1. Tlie differences between M. h. tenuiceps and M. harlani con- 
tained in the Museum of History, Science and Art of Los Angeles are 
based on a comparison between individuals in which the coronal and 
parieto-squamosal sutures have closed. In the Nebraska skull the 
coronal suture is still distinctly to be seen. Another apparently char- 
acteristic feature of a more advanced age, which is fairly constant in 
the Rancho La Brea series, is the degree of pitting of the palate. In 
the typical slender skulls this is distinctly more developed than in the 
Nebraska specimen. In no. 695 the palate is too badly worn to indi- 
cate this with certainty. 

2. In the three, possibly four skulls, which are considered to rep- 
resent M. h. tenuiceps, the palate posterior to the fifth tooth is nar- 
rowed decidedly. This portion of the palate in Brown's specimen is 
more as in the broader types of skulls from Rancho La Brea. 

The amount of variation exhibited by the fourth inferior tooth 
in specimens of the Museum of History, Science and Art of Los 
Angeles support the previous contention that it is unsafe to base any 
primary specific characters on this tooth. It must be admitted, how- 



1917] 



Stock: Skull Structure of Mylodont Sloths 



173 



ever, that in the great series at Los Angeles there is no indication of 
a fourth inferior tooth having exactly the same development as in 
Brown's specimen. 

It appears undesirable to interpret the characters, given as diag- 
nostic of the subspecies, as of sex value on account of the obvious 
difficulty of explaining the apparent preponderance of one of the 
sexes. 

The slender skulls, represented by nos. 642, 643, and 646, as 
contrasted with a typical broad skull of M. harlani, may be compar- 
able to dolichocephalic and bracbycephalic types in other groups of 
animals. 

Measurements of Skull 



Cranium 

Length from anterior end of 
maxillaries to posterior end of 
occipital eonyles 

Length of palate from anterior 
end of maxillaries to post- 
palatine notch 

Greatest width of maxillaries, 
measured across palate anter- 
ior to first teeth 

Least width of palate posterior 
to fifth tooth 

Least distance across ventral 
margin of pterygoid plates 

Greatest width of muzzle 

Least width behind postorbital 
processes 

Mastoid width above stylohyal 
processes 

Greatest width across occipital 
condyles 

Height, measured from plane of 
basioccipital to dorsal plane .... 

Least distance from fifth super- 
ior tooth to middle of post- 
palatine notch 

Mandible 

Greatest length of symphysis .... 

Greatest predental widtli 

Depth of ramus between third 
and fourth inferior teeth, 
measured normal to inferior 

margin 

a, approximate. 



o 



Is J 

a> . 
-~ o o 
. -* J2 

fi to S3 
■OS 



fuaft 

'3 Km 
c . 

°" to o 



n92.7 
98. 



a,33. 



495. mm. 


486.4 


471.5 


fl.459.4 


«492.8 


219. 


217.6 


213.2 




0216.3 


136.4 


ol38.6 






125.4 


52.7 


57.4 
111.7 


«55.5 




67. 


133.5 


(il35. 




al31. 


al31. 


94.6 


97.7 


91.7 


rtlOO. 


108. 


184.5 


al84. 


178. 


al67.7 


184.5 


131. 


132. 


118.5 


0.122.8 


128.2 


134.8 


«131.8 


129.6 


128. 


138.2 


45.6 


47.3 


50.8 




53.4 



174 University of California Publications in Geology [Vol. 10 

Measurements of Dentition 

< < K < < 

a. Kf q a, Km g Mm wm 

** N o o ^if) o T! ** o 

.f£ . w O)J3 S-s'.a 

•Ort • C a! ,_jdc3 ■ O cj 

M-, anteroposterior diameter a?33.5 mm o31.8 

M5, transverse diameter a'18.3 20. 

M 2 , anteroposterior diameter a28.6 a23.2 28.3 

M 2 , transverse diameter o24.3 o20.3 23. 

M 1 , anteroposterior diameter 22. a22.4 

M 1 , transverse diameter 23.3 23.7 

M5, anteroposterior diameter o27.3 22.3 25.6 

M-, transverse diameter o20. 18. 22.4 

Length of superior series, from anterior end 
of first alveolus to posterior end of fifth 

alveolus 146.5 al37. 

Length of superior series, from anterior end 
of second aveolus to posterior end of fifth 

alveolus 119.6 110.8 120.6 

Mj, anteroposterior diameter al4.5 

Mj, transverse diameter al5.4 

Mj, anteroposterior diameter 25.7 

M;, transverse diameter 20.2 

M5, diameter of occlusal surface normal to 

greatest diameter 17. 

Mj, anteroposterior diameter 52. 

Mj, greatest diameter of anterior lobe «28.7 

Mj, greatest diameter of posterior lobe al9.7 

Length of inferior series, alveolar measure- 
ment 130.4 

a, approximate. al, alveolar measurement. 

CONCLUSIONS 

The following additional facts have been noted with reference to 
the rnylodont skull series from Rancho La Brea : 

Three, possibly four, crania contained in the Museum of History, 
Science and Art of Los Angeles, are recognized as representing a form 
subspecifically distinct from typical Mylodon Aiarlani. 

These crania differ from M. harlani of Rancho La Brea in exhibit- 
ing in combination a rather narrow brain-case with a narrow palate 
posterior to the fifth tooth. 

The Nebraska skull described by Brown can not be referred to 
the new subspecies from Rancho La Brea, since its characters, although 
in certain respects approaching those of the latter, are still quite 
distinct. The Nebraska specimen presumably represents Mylodon 
harlani, but may belong in a subspecies distinct from the two known 
to occur at Rancho La Brea. 

Transmitted December 23, 1916. 



EXPLANATION Or PLATE 3 
Mylodon harlani tenuiceps, n. subsp. Cranium, no. 642 M. H. S. A., superior 
view, approximately three-eighths of natural size. Eanelio La Brea Beds, Cali- 
fornia. Photograph by L. E. Wyman. 



[176] 



UNIV. CALIF. PUBL, BULL. DEPT. GEOL 



[STOCK] VOL. 10, PL. 3 




EXPLANATION OF PLATE 4 
Mylodon harlani tenuiceps, n. subsp. Cranium, no. 642 M. H. S. A., inferior 
view, approximately three-eighths of natural size. Eancho La Brea Beds, Cali- 
fornia. Photograph by L. E. Wyman. 



[178] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL 



[STOCK] VOL. 10, PL. 4 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 12, pp. 179-183 Issued March 23, 1917 



SYSTEMATIC POSITION OF SEVERAL 
AMERICAN TERTIARY LAGOMORPHS 

BY 

LEE RAYMOND DICE 




UNIVERSITY OF CALIFORNIA PRESS 
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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 12, pp. 179-183 Issued March 23, 1917 



SYSTEMATIC POSITION OF SEVERAL 
AMERICAN TERTIARY LAGOMORPHS 

BY 

LEE RAYMOND DICE 



CONTENTS 

Introduction 

Archaeolagus, new genus 

Hypolagus, new genus 

Oieolagus, new genus 

INTRODUCTION 

A study of the teeth of many lagomorphs, including both Recent 
and extinct forms, has shown that the enamel patterns furnish re- 
markably constant diagnostic characters. Each species commonly 
possesses a distinct tooth pattern and there are usually striking dif- 
ferences separating the genera. The most important characters are 
the number and form of the re-entrant angles of P s , the number of 
re-entrant angles of P-, and the depth and amount of crenation of the 
re-entrant angles of the upper molariform teeth. 

Until a few years ago nearly all the Leporidae were included in 
the genus' Lepus, but more recently the family has been divided into 
a number of distinct genera. A critical study of two fossil species 
previously placed in the genus Lepus shows that they cannot be re- 
tained in 'that' genus as it is now restricted, and new genera- are there- 
fore proposed for their reception:- 

" Another species of lagomorph previously referred to Palaeolagus 
is shown by the characters of the enamel patterns to belong to the 
family Oehotonidae, but it differs from any known form in that family, 
and for it also a new generic name is proposed. 




180 University of California Publications in Geology [Vol.10 

The new genera are based largely on the characters of the teeth, 
particularly on differences in the enamel patterns, but, where parts 
of the skeleton are known, decided differences from other lagomorphs 
are found also. 

The material on which the following descriptions are based is 
located in the Palaeontological Collections of the University of Cali- 
fornia. Thanks are due Dr. J. C. Merriam for advice and criticism 
during the progress of the study. The drawings of the teeth have 
been made with a camera lucida on a microscope magnifying twelve 
diameters, and the pattern of each tooth has been drawn separately, 
from a point of view parallel to the length of the tooth. 

ARCHAEOLAGUS,i new genus 

Type species Lepus ennisianus Cope 

Abundant in the Upper Oligocene John Day beds of Oregon. Be- 
sides the descriptions- and figures 3 given by Cope there have been 
available in this study a considerable number of specimens from the 
John Day beds now in the palaeontological collections of the University 
of California. 




Fig. 1. Archaeolagus ennisianus (Cope). Left upper molariform teeth, X 3. 
Univ. Calif. Coll. Vert. Palae. no. 1501. John Day beds, Oregon. 

P= with a shallow groove on its anterior face. Upper molariform 
teeth with interior re-entrant angles not crenated and not extending 
as far as half across the crowns. On these teeth there are often enamel 
crescents exterior to the outer ends of the re-entrant angles, and some- 
times the backs of the crescents connect with the outer side of the 
teeth. P,: shows an exterior re-entrant angle extending about half way 
across the tooth. Anterior to this is a shallow groove, which is also 
on the outer surface. The inner border of the tooth is without re- 
entrant angles, differing in this respect from Palaeolagus. Mj is im- 
perfectly divided into two columns by a deep exterior re-entrant angle. 
There is very little cement on any of the teeth. 

1 dpx a "> s i primitive; \ayQs, hare. 

2 Cope, E. D., Bull. U. S. Geol. Sur. Terr., vol. 6, pp. 385-386 (1882). 

s Cope, E. D., Tertiary vertebrata, Rept. U. S. Geol. Surv. Terr., vol. 3, bk. 1, 
pi. 64, figs. 11 and 11a; pi. 66, figs. 29a, 29&, and 29c (1884). 



1917] 



Dice: American Tertiary Lagomorphs 



181 



The posterior part of the jaw is very different in shape from that 
of any living lagomorph. The region for the attachment of the mass- 
seter muscle is very weakly developed, and, as stated by Cope,' the 
masseteric fossa is entirely posterior to the tooth row. 

(m 

Fig. 2 Fig. 3 

Fig. 2. Archaeolagus ennisianus (Cope). Left lower molariform teeth (except 
M 5 ), X 3. Univ. Calif. Coll. Vert, Palae. no. 1267, X 3. John Day beds, Oregon. 

Fig. 3. Archaeolagus ennisianus (Cope). Eight M, and M 5 , X 3. Univ. Calif. 
Coll. Vert. Palae. no. 339, X 3. John Day beds, Oregon. 

The skull indicates that the John Day animal had approximately 
the size of Sylvilagus floridanus. However, the skull is more slender, 
and the braincase has a much smaller capacity than that of any Recent 
rabbit. 

HYPOLAGUS,"' new genus 

Type species Lepus veins Kellogg' 5 

One jaw is known from the Middle Miocene, Virgin Valley beds. 
Two jaws, one of them the type specimen, and one upper molar are 
known from the Pliocene, Thousand Creek beds. Both localities are 
in Humboldt County, Nevada, 

In this genus P3 has two exterior re-entrant angles, neither of 
which extends over half way across the tooth. The posterior angle is 
much deeper than the anterior. There are no grooves on the inner 
surface of the tooth. The upper molar has the re-entrant angle ex- 

Fig. 4 Fig. ■) 

Fig. 4. Hypolagus vetus (Kellogg). Left lower molariform teeth, X 3. Univ. 
Calif. Coll. Vert. Palae. no. 12567. Thousand Creek beds, Nevada, 

Fig. 5. Hypolagus vetus (Kellogg). Upper molariform tooth, X 3. Univ. 
Calif. Coll. Vert. Palae. no. 21868. Thousand Creek beds, Nevada. 

tending about half way across the crown and the enamel in the angle 
is coarsely folded. Cement is well developed on the teeth, particularly 
on the specimens from Thousand Creek. 

< Cope, E. D., Bull. U. S. Geol. Surv. Terr., vol. 6, p. 385 (1882). 
•"• 0tt6, under; \ayu>s, hare. 

« Kellogg, L., Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, p. 436, fig. 20 (1910). 




182 University of California Publications in Geology [Vol.10 



The posterior re-entrant angle of P 5 in the Virgin Valley specimen 
is somewhat different from that in the type specimen, and the shape 
of P3 differs in the two. There are also some differences in the com- 
parative size of various other teeth. It may be that the Virgin Valley 
form should be placed in a separate species, but the amount of material 
now at hand is too scanty to permit a satisfactory determination of 
this point. 

P3 in Hypolagus differs from the corresponding tooth in Archae- 
olagus in being proportionally shorter and broader, although the 
enamel pattern is very similar in the two genera. Hypolagus further 
differs from Archaeolagus in having the re-entrant angles of the 
molars coarsely folded, whereas they are simple in the John Day 
species. Also, in Hypolagus the region of the jaw for the attachment 
of the masseter muscle is well developed, as in modern rabbits, and is 
not weak, as in Archaeolagus. 

In the characters of the teeth and skeleton Hypolagus is in general 
more simple than Lepus, and may be considered a form near the 
probable ancestor of that genus as well as of several other modern 
genera. Archaeolagus is a form much more primitive than Hypolagus, 
and might well have been its progenitor. 



A single specimen, consisting of part of a lower jaw and the teeth, 
except M3, is known from the Middle Miocene, Virgin Valley beds of 
Humboldt County, Nevada. 



Fig. 6. Oreolagus nevadensis (Kellogg). Lower molariform teeth (except M,), 
X 3. Univ. Calif. Coll. Vert. Palae. no. 12575. Virgin Valley beds, Nevada. 

The form is evidently a lagomorph, as the lower molar teeth are 
formed of two columns, one posterior to the other. The species, how- 
ever, seems to have closer affinities to the Ochotonidae than to the 
Leporidae, for the posterior column of the molariform teeth is at- 
tached to the anterior column in a narrow neck, rather than by a 
broad union extending nearly across the tooth, as in the Leporidae. 

7 cipos, mountain ; \ayu>s, hare. 

s Kellogg, L., Univ. Calif. Publ. Bull. Dept. Geo!., vol. 5, p. 485, figs. 19a and 
196 (1910). 



OREOLAGUS,? new genus 
Type species Palaeolagus nevadensis Kellogg' 



.8 




1917] 



Dice: American Tertiary Lagomorphs 



183 



Pj has a re-entrant angle originating on the antero-exterior border 
of the tooth and extending about half way across. This tooth is rela- 
tively much smaller than is usual in lagomorphs, being little, if any, 
larger than the anterior column of P 5 . Its enamel pattern, also, is 
very peculiar, differing radically from that of any other known 
lagomorph. 

Oreolagus must be considered an aberrant ochotonid, probably not 
ancestral to any known species, which appeared in North America long 
before the appearance here of the modern genus Ochotona. 



Transmitted December 20, 1916. 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

IN 

GEOLOGY 

Vol. 10, No. 13, pp. 185-190, plate 5 Issued November 30, 1917 



NEW FOSSIL CORALS FROM THE 
PACIFIC COAST 



BY 

JORGEN O. NOMLAND 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



Note. — The University of California Publications are offered in exchange for the publi- 
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Cited as Univ. Calif. Publ. Bull. Dept. Geol. 

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VOLUME 6. 

1. The Condor-like Vultures of Rancho La Brea, by Loye Holmes Miller 15« 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part 'I. — Geologic History 50c 

3. The Geology of the Sargent Oil Field, by William F. Jones : 25c 

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Loye Holmes Miller - 10c 

5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe, by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of Rancho La Brea, by John C. 

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7. A Collection of Mammalian Remains from Tertiary Beds on the Mohave Desert, 

by John C. Merriam. 

Nos. 6 and 7 in one cover , 10c 

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and Tejon North of Mount Diablo, by Roy E. Dickerson 5c 

9. Neocolemanite, a Variety of Colemanite, and Howlite from Lang, Los Angeles 

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10. A New Antelope from the Pleistocene of Rancho La Brea, by Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part II. — Vertebrate Faunas 1.00 

12. A Series of Eagle Tarsi from the Pleistocene of Rancho La Brea, by Loye Holmes 

Miller _. 10c 

13. Notes on the Relationships of the Marine Saurian Fauna Described from the Triassic 

of Spitzbergen by Wiman, by John C. Merriam. 

14. Notes on the Dentition of Omphalosaurus, by John C. Merriam aEd Harold C. Bryant. 

Nos. 13 and 14 in one cover 15o 

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17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5c 

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19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25e 

VOLUME 7. 

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2. Pseudostratifieation in Santa Barbara County, California, by George Davis Louder- 

back , 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Rancho La Brea, by John C. 

Merriam .'. '. .TT. 5c 

4. The Neocene Section at Kirker Pass on the North Side of Mount Diablo, by Bruce 

L. Clark 15c 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60e 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

I N 

GEOLOGY 

Vol. 10, No. 13, pp. 185-190, plate 5 Issued November 30, 1917 



NEW FOSSIL CORALS FROM THE 
PACIFIC COAST 

BY 

JORGEN O. NOMLAND 



CONTENTS 

PAGE 



Introduction 185 

Astrangia boreas, n. sp 185 

Astrangia grandis, n. sp 186 

Astreopora occidentalis, n. sp 187 

Caryophyllia oregonensis, n. sp 187 

Dendrophyllia calif orniana, n. sp 188 

Astoria Oligocene corals 189 



INTRODUCTION 

In an earlier paper 1 the writer has summarized the known corals 
of the Pacific Coast Cretaceous and Tertiary. More recently a large 
and important coral fauna has been described by Dr. T. W. Vaughan 2 
from the Pliocene of Carrizo Creek in the southern part of California. 
Since the appearance of these publications a few new species have been 
discovered and other forms have become available. These species are 
described in the present paper. 

Heretofore by far the greater proportion of corals have been de- 
scribed from the Tejon Eocene. It is worthy of note that two of the 
new species here described are from the Oligocene. Several other 
forms are known to be present in the Oligocene faunas, but the only 
material obtained up to the present time is not sufficient for specific 
description. 

1 Nomland, J. O., Corals from the Cretaceous and Tertiary of California and 
Oregon, Univ. Calif. Publ. Bull. Dept. Geol., vol. 9, no. 5, 1916. 

2 Vaughan, T. W., The Reef-Coral Fauna of Carrizo Creek, Imperial County, 
California, and its Significance, U. S. Geol. Surv., Prof. Paper 98, 1917. 



186 



University of California Publications in Geology [Vol. 10 



ASTRANGIA BOREAS, n. sp. 
Plate 5, figures 2a, 2b, 2c 
Type, no. 11324, Univ. Calif. Coll. Invert. Palae. From the Treadwell mine, 
Alaska. 

Colony with base somewhat encrusting but extending upwards as 
irregular, short branches ; reproduction by basal expansion and also by 
buds arising irregularly from the sides and within the calices of older 
corallites ; corallites, frequently narrow near base, becoming wider 
above. Costae almost obsolete, smooth, on some portions visible nearly 
to the base, of the same number as the septa. Septa numerous, thin, 
dentate, lateral faces with few small granules, arranged in four or 
five cycles, of which the first two reach the columella, some of the septa 
of the later cycles fused to the earlier cycles without regularity. Calice 
deep, nearly circular. Wall rather thin. Columella well developed, 
spongy, rather small in proportion to the size of the calice. Greater 
transverse diameter of one of the largest calices of type, 15.5 mm. ; 
lesser transverse diameter, 12.5 mm. ; height of corallites varies greatly. 

Occurrence. — A letter dated June 20, 1890, sent to Professor Jo- 
seph LeConte by the collector, M. A. Knapp, gives the following 
description of the locality at which the specimens were found, "On 
the quartz croppings of this (Treadwell mine) ledge, 175-180 feet 
above sea-level and about 500 yards from shore. ' ' Pleistocene ( ? ) , 
Douglas Island, southeastern part of Alaska. 

ASTRANGIA GRANDIS, n. sp. 

Plate 5, figures 5a, 5b 

Type, no. 11325, a well preserved specimen in Calif. Acad. Sci. Coll. from 
locality 76, at Waldorf Asphalt mine, in hills about four or five miles south of 
Guadalujne, Santa Barbara County, California. 

Corallum incrusting a fragment of rather soft shale saturated with 
asphalt ; base expanding as a thin coating ; corallites large, new ones 
apparently arising from basal expansion of the older ; calicular fossa 
deep, elliptical. Externally ornamented by distinct, coarsely granu- 
late somewhat angular costae extending to the base : interspaces wide, 
occasionally with a small granulate rib. Wall rather thin, slightly 
thickened internally. Septa thin, coarsely dentate ; lateral faces with 
numerous pointed granules ; in about five incomplete cycles, of which 
the first three reach the columella ; fourth cycle fused to the earlier 
cycles; fifth small, free. Columella rather dense, not large in propor- 



1917] Nomland: New Fossil Corals from the Pacific Coast 187 



tion to size of the calices, composed of fascicles with additions from the 
septal ends. Dimensions : greater transverse diameter of calices, about 
19 mm. ; lesser transverse diameter of calices, 13 mm. ; altitude of 
corallites, approximately 17 mm. 

Occurrence. — Middle Fernando, Pliocene, Guadalupe, Santa Bar- 
bara County, California. 

ASTEEOPOEA OCCIDENTAL1S, n. sp. 
Plate 5, figures la, lb, lc 
Type, no. 11323, in Univ. Calif. Coll. Invert. Palae., from ocean beach near 
Newport, Oregon. Material purchased from John Lumis, Ashland, Oregon. 

Corallum a water-worn pebble largely replaced by chalcedonic 
quartz ; upper surface of corallites not present, but internal structure 
remarkably well preserved. Corallites small, 1.25 to 1.50 mm. in 
diameter, long and comparatively straight, usually circular but some- 
times subcircular in outline, surrounded by a large proportion of very 
cellular exotheca. Wall thin with distinct but not numerous perfora- 
tions, dictinctly marked off from surrounding exotheca. Septa twelve, 
short and thick, extending uniformly throughout the length of coral- 
lites in two cycles of which the primary is much more prominent, a 
third cycle of septa represented by costules ; along the inner margin of 
the first cycle of septa nodes occurring at regular intervals project on 
the sides and inward, giving a dentate appearance ; where these are 
cut in cross-section pali seem to be present on the inner ends of the 
primaries; interseptal loculi wide, thin tabulae well-developed, .75 to 
1 mm. apart; spaces between the tabulae open. Columella absent. 
Dimensions of corallites: diameter from .8 mm. to 1.1 mm. ; length not 
known. 

Occurrence. — On ocean beach near Newport, Oregon. Probably 
from the Tertiary deposits in that vicinity. 

CAEYOPHYLLIA OEEGONENSIS, n. sp. 
Plate 5, figures 3, 4 
Type specimen, no. 11326, in invertebrate palaeontology collections of 
California Academy of Sciences, San Francisco. Prom Smith 's Point, Astoria, 
Oregon. 

Corallum short, subflabellat<\ elliptical in cross-section, base sub- 
acute with attachment scar visible ; calicular fossa deep ; wall thin and 
fragile. Costae prominent, sharp, coarsely granular, corresponding 
to all the septa ; those corresponding to the twelve principal septa much 



188 University of California Publications in Geology [Vol. 10 



larger than the others ; intercostal grooves narrow. Septa forty-eight, 
faces granulate, irregularly bent, the upper margins projecting con- 
siderably above the corallum wall, giving a saw-tooth appearance ; in 
four complete cycles, of which the first two reach nearly to the colu- 
mella, fourth cycle short, free. Pali thin and indistinct, attached to 
the septa, before the margins of the first three cycles, which are of 
nearly the same diameter. Columella consisting of a few heavy scat- 
tered twisted trabecular Dimensions of type, which is a small speci- 
men : maximum transverse diameter, 9.5 mm. ; lesser transverse 
diameter, 6 mm. ; height, approximately 8 mm. 

Three other fossil corals of this genus have been described from 
the Pliocene and Pleistocene of the Pacific Coast — Caryophyllia arnoldi 
Vaughan, Caryophyllia calif or nica Vaughan, Caryophyllia pedroensis 
Vaughan. The species here described differs from these forms greatly. 

Occurrence. — In a fine soft black shale, on street grade above 
Smith 's Point, northwestern Oregon ; Astoria Series, Oligocene. 

DENDROPHYLLIA CALIFORNTANA, n. sp. 
Plate 5, figures 6a, 6b 

Type, no. 11190, Univ. Calif. Coll. Invert. Palae. From locality 1131, one- 
half mile south -southwest of the town of Walnut Creek, Contra Costa County, 
California. 

Corallnm consisting of irregularly branching stems. Calices nu- 
merous but not crowded, subcircular, approximately equal in size, 
rising only slightly above the surface, of medium depth, occurring 
apparently on all sides of the stems without definite order of arrange- 
ment. "Wall rather thin, spongy. Costae granulate, nearly equal in 
size, well developed, but due to the large number of pores in the wall 
ribs may not "be continuous but interrupted or deflected. Septa 
about forty-eight, granulate, rather heavy, arranged in four cycles, 
of which the first three reach the columella, fourth cycle regularly 
fused to the third. Columella spongy, occupying a large part of the 
calice. Dimensions of calices, about 6.5 mm. 

This species has some of the characters of Dendrophyllia hannibali 
Nomland, which also occurs in the Oligocene of the Pacific Coast. It 
may, however, readily be distinguished from that form by the more 
numerous calices, finer costae, and the large spongy columella. From 
Dendrophyllia tejonensis Nomland of the Tejon Eocene it differs in 
the spongy wall, greater number of calices, and larger columella. 



1917] Nomland: New Fossil Corals from the Pacific Coast 189 



Occurrence. — At locality 1131, near base of Agasoma gravidum 
zone, Oligocene. 

This form occurs at the type locality of Siderastrea clarki Nomland 
and is associated with such characteristic Oligocene species as Agasoma 
gravidum (Gabb), Antigona mathewsonii (Gabb), Ancellaria fishii 
Gabb, Dosinia mathewsonii Gabb, Dosinia whitneyi (Gabb), Molopo- 
phorus biplioatus Gabb, Mytilus mathewsoni Gabb, Fvsinus (Prisco- 
fusus) hecoxi Arnold. 

BALANOPHYLLIA, sp. 

It is of interest to note that specimens of Balanophyllia have been 
discovered recently in beds of middle Fernando, Pliocene, at Fugler 
Point, eight miles southeast of Santa Maria, Santa Barbara County, 
California. This genus has heretofore been unknown in the Tertiary 
deposits of the Pacific Coast later than the Oligocene. This form is 
associated with a large typical Fernando fauna. 2 

ASTOEIA OLIGOCENE COEALS 

In the Oligocene of the Astoria group of southwestern "Washington 
several species of corals are present, but the material is only generically 
identifiable. These are found associated 'with Dcndrophyllia hannibali 
Nomland or in the same series of beds as that species. The following 
forms, occurring with a large molluscan fauna, have been determined : 
Balanophyllia, sp., Plabellum, sp., Paracyathus, sp., Pocillopora (?), 
sp., Sphenotrochus ( ?), sp., Trochocyathus (two species). 



3 See U. S. Geol. Surv. .Bull. 322, p. 60. 



EXPLANATION OF PLATE 5 

Fig. la. Astreopora occidentalis, n. sp. Longitudinal view of polished sur- 
face Univ. Calif. Coll. Invert. Palae., no. 11323. X 2. 

Pig. lb. Astreopora occidentalis, n. sp. Cross-section view of polished sur- 
face of same specimen as figure la. X 7. 

Fig. lc. Astreopora occidentalis, n. sp. Cross-section of specimen shown in 
figure la. X 2. 

Fig. 2a. Astrangia boreas, n. sp. General view of type specimen. Univ. 
Calif. Coll. Invert. Palae. no. 11324; Pleistocene ( ?) . Natural size. 

Fig. 26. Astrangia boreas, n. sp. View of specimen seen in figure 2a, show- 
ing denticles on septal margins. X 2. 

Fig. 2c. Astrangia boreas, n. sp. Enlarged calicular view of specimen seen 
in figure 2. X 2. 

Fig. 3. Caryophyllia oregonensis, n. sp. Upright view of type specimen. 
Calif. Acad. Sci. Coll. no. 11326; Oligocene. X 2. 

Fig. 4. Caryophyllia oregonensis, n. sp. Cross-section view of a small speci- 
men. X 2. 

Fig. 5a. Astrangia grandis, n. sp. Enlarged calicular view of type speci- 
men. Calif. Acad. Sci. Coll. no. 11325; Fernando Pliocene. X 2. 

Fig. 5b. Astrangia grandis, n. sp. General view of type. Natural size. 

Fig. 6<j. Dendrophyllia calif orniana, n. sp. Upright view of type. Univ. 
Calif. Coll. Invert. Palae. no. 11190. Oligocene. Natural size. 

Fig. 6b. Dendrophyllia calif orniana, n. sp. Enlarged view of calices of type 
specimen seen in figure 6a. X 3. 



[190] 



UNIV. CALIF, PUBL. BULL. DEPT. G&OL 



[NOMLAND] VOL. 10, PL. 5 




UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 14, pp. 191-254, 2 text-figs., pis. 6-12 Issued April 19, 1917 



THE ETCHEGOIN PLIOCENE OF 
MIDDLE CALIFORNIA 



BY 

JORGEN O. NOMLAND 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

Note. — The University of California Publications are offered in exchange for the publi 
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Otto Harrassowitz R. Friedlaender & Sohn 
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Geology. — Andrew C. Lawson and John C. Meeriam, Editors. Price, volumes 1-7, $3.50, 



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Cited as Univ. Calif. Publ. Bull. Dept. Geol. 

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A list of titles in volumes 1 to 5 will be sent upon request. 

VOLUME 6. 

1. The Condor-like Vultures of Rancho La Brea, by Loye Holmes Miller 15* 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part I. — Geologic History > 50c 

3. The Geology of the Sargent Oil Field, by William F. Jones 25c 

4. Additions to the Avifauna of the Pleistocene Deposits at Fossil Lake, Oregon, by 
Loye Holmes Miller 10c 



5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe, by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of Rancho La Brea, by John C. 

Merriam. 

7. A Collection of Mammalian Remains from Tertiary Beds on the Mohave Desert, 

by John C. Merriam. 

Nos. 6 and 7 in one cover 10c 

8. The Stratigraphic and Faunal Relations of the Martinez Formation to the Chieo 

and Tejon North of Mount Diablo, by Roy E. Dickerson 5c 

9. Neocolemanite, a Variety of Colemanite, and Howlite from Lang, Los Angeles 

County, California, by Arthur S. Eakle 10c 

10. A New Antelope from the Pleistocene of Rancho La Brea, by Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 
Nevada, by John C. Merriam. Part II. — Vertebrate Faunas 1.00 



12. A Series of Eagle Tarsi from the Pleistocene of Rancho La Brea, by Loye Holmes 

Miller _ _. 10c 

13. Notes on the Relationships of the Marine Saurian Fauna Described from the Triassic 

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14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13-and 14 in one cover 15a 

15. Notes on the Later Cenozoic History of the Mohave Desert Region in Southeastern 

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17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg . 5c 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25c 



VOLUME 7. 

1. The Minerals of Tonopah, Nevada, by Arthur S. Eakle 25c 

2. Pseudostratification in Santa Barbara County, California, by George Davis Louder- 

back '. 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Rancho La Brea, by John C. 

Merriam : 5c 

4. The Neocene Section at Kirker Pass on the North Side of Mount Diablo, by Bruce 

L. Clark _ 15c 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60e 



x 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 14, pp. 191-254, 2 text-figs., pis. 6-12 Issued April 19, 1917 



BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 



THE ETCHEGOIN PLIOCENE OF MIDDLE 
CALIFORNIA 

xljsoriian \n$tj f 
A? 

JOEGEN O. NOMLAND Ify MAY 4" '1917 # 

\ 4f J 

CONTENTS ' ^ 

PAGE 

Introduction , - 192 

Previous work — - 193 

Eelation of the Jacalitos to the Etehegoin 195 

Etehegoin group of Middle California 197 

Areal distribution 197 

Eelation to adjoining formations 200 

Eelation to the Santa Margarita ( ? ) 200 

Eelation to the Tulare 202 

Thickness 203 

Structure - 205 

Lithology of the Etehegoin 206 

Sandstone, clay, and conglomerate 206 

Coal and carbonaceous deposits 207 

Ehyolitic tuffs 208 

Gypsum 209 

Limestone 210 

Invertebrate fauna 210 

Invertebrate zones 210 

Etehegoin fauna west of the Diablo Eange 214 

Fauna of lacustrine( ?) beds 215 

Eange of temperature and depth 216 

Serpula(?) reef 216 

Comparative table showing stratigraphic relationship of faunal zones 

south of Coalinga 216 

Vertebrate fauna 217 

Faunal list of the Etehegoin of the Coalinga district 218 

Age and correlation of the Etehegoin 223 

History of correlation 223 

Age determination ! 225 

Correlation with other Pliocene formations 226 



192 University of California Publications in Geology [Vol. 10 

PAGE 

Summary : 227 

Occurrence of Etchegoin species by localities in the Coalinga region 227 

Description of Etchegoin invertebrate localities 228 

Description of species 231 

Anodonta nitida, n.sp 231 

Pecten egregius, n. sp 231 

Pecten proteus, n.sp 232 

Maeoma inquinata affinis, n.var 233 

Semele fausta, n.sp 233 

Thracia formosa, n.sp. 234 

Fissuridea unica, n.sp 234 

Tegula (Chlorostoma) pulcella, n.sp 235 

Chrysodomus packardi, n.sp 235 

Murex concinna, n.sp 236 

Murex tethys, n.sp 236 

Trophon belcheri avitum, n.var 237 

Cancellaria crassa, n.sp 237 

Cancellaria fernandoensis tribulis, n.var 238 

Pecten etchegoini Anderson 239 

Serpula (?), sp 239 

Cancellaria rapa, n.sp 240 



INTRODUCTION 

The Etchegoin group of California has for a number of years 
attracted the attention of palaeontologists and geologists because of 
its somewhat uncertain position with respect to the other divisions of 
the late Tertiary. Especially has it been difficult to ascertain the time 
relation between these beds and the Pliocene sections along the outer 
side of the Coast Ranges south of San Francisco. The Etchegoin has 
been considered the equivalent of the San Pablo Miocene by certain 
writers, while by others it is held to represent the stage of the Purisima 
and Merced Pliocene. Although excellent work has been done on the 
Etchegoin invertebrate fauna by several investigators, the difficulties 
of pioneer work have made it impossible to secure the large represen- 
tation now available to the writer. The determination of the age of 
this group has recently been facilitated by the finding of remains of 
land mammals at several horizons in a predominantly marine section. 
The Etchegoin has come, therefore, in many ways to have unusual 
significance in the consideration of the problem of the later Tertiary 
of middle California. 

Due to the peculiar local character of many of the Pliocene deposits 
of the Pacific Coast, correlation by lithology, except for very short 
distances, becomes extremely hazardous or impossible. For the ex- 



1917] Nomland: The Etchegoin Pliocene of Middle California 193 



tension of our knowledge of the stratigraphy and palaeontology of 
this system it therefore becomes important to make a detailed study 
of the successive faunal zones in the most complete section known. 
Aside from the importance of finding horizons bearing vertebrate 
remains in the same section with those containing marine forms, it is 
evident that the sequence at Coalinga is the most important in middle 
California. The strata have been much folded, due to important dias- 
trophic movements in post-Pliocene time. Extensive outcrops of the 
Pliocene south of Coalinga show exposures aggregating over ten 
thousand feet of strata, this being the greatest thickness of sediments 
belonging to this period described in America. 

In the mapping of the Coalinga district by the members of the 
United States Geological Survey the " Jacalitos" formation was desig- 
nated as a separate unit. A more extensive faunal and stratigraphic 
study has shown that the "Jacalitos" and the Etchegoin beds are 
closely linked in diastrophic history, and the former has therefore 
been included as a lower part of the Etchegoin in the present paper. 
The whole Etchegoin, contrary to the practice of many earlier geolo- 
gists, is here placed in the Pliocene. 

During the progress of the study of this problem the writer has 
frequently received the criticism and advice of Professor J. C. Mer- 
riam. The assistance derived from simultaneous study by him of the 
vertebrate material from Coalinga has been very valuable. Much 
help and encouragement both in the field and in the laboratory have 
been given by Dr. B. L. Clark, Instructor in Palaeontology at the 
University of California. The writer is indebted to Mr. R. W. Pack 
of the United States Geological Survey for information concerning the 
location of numerous excellent fossil localities in the lower Etchegoin. 

PREVIOUS WORK 

The Etchegoin beds of Middle California were first described in 
two publications by F. M. Anderson. 1 A fuller description with a 
summary of previous geologic and palaeontologic work was given by 
Ralph Arnold and Robert Anderson 2 in their report on the geology 
and oil resources of the Coalinga District. 

1 Anderson, F. M., A stratigraphic study of the Mount Diablo range of Cali- 
fornia, Proc. Calif. Acad. Sci., 3d ser., vol. 2, no. 1, 1905; A further study in the 
Mount Diablo range of California, Proc. Calif. Acad. Sci., 4th ser., vol. 3, 1908. 

2 Arnold, Ealph, and Anderson, Eobert, Geology and oil resources of the 
Coalinga District, Fresno and Kings counties, California, U. S. Geol. Surv. Bull. 
398, 1910. 



194 University of California Publications in Geology [Vol. 10 



The literature dealing with the Pliocene of Middle and Northern 
California, but not including the Etchegoin of the Coalinga District, 
has recently been summarized by Bruce Martin. 3 Since the paper by 
Martin was written, several other publications have appeared de- 
scribing the California Pliocene which will here be mentioned briefly 
according to date of publication. 

A short paper on the Fernando group, published by W. A. Eng- 
lish 4 in 1914, deals essentially with the Pliocene at Elsmere Creek 
about thirty miles northwest of Los Angeles, California, and presents 
faunal lists which have been found very valuable for correlation pur- 
poses in the present paper. 

In the course of their investigation of the geology and economic 
resources of Middle California a short bulletin has been issued by 
R. W. Pack and W. A. English/' In this paper almost no palaeonto- 
logic discussion is entered into and the various horizons of upper 
Miocene and lower Pliocene are considered as one group, which is 
referred to the upper Miocene. 

The Etchegoin is briefly referred to by P. M. Anderson and Bruce 
Martin 1- ' in a publication on the San Juan district, San Luis Obispo 
County, California, and a few species described from the Pliocene near 
Coalinga. 

Professor J. C. Merriam 7 has recently described the occurrence of 
vertebrates in zones having a definite relationship to invertebrate zones 
north of Coalinga. The forms described from the Etchegoin occur 
in the area covered by the study of the writer in the present paper. 
Professor Merriam brings forth evidence indicating the Pliocene age 
of the Jacalitos and Etchegoin. In later papers Professor Merriam 8 
describes a species of Pliohippus from the upper Etchegoin. 

In a recent paper on the geology of the region bordering the west- 



3 Martin, Bruce, The Pliocene of Middle and Northern California, Univ. 
Calif. Publ. Bull. Dept. Geol., vol. 9, no. 15, 1916. 

4 English, Walter A., The Fernando Group near Newhall, California, Univ. 
Calif. Publ. Bull. Dept. Geol., vol. 8, no. 8, 1914. 

5 Pack, E. W., and English, W. A., Geology and oil prospects in Waltham, 
Priest, Bitterwater, and Peaehtree valleys, California, U. S. Geol. Surv. Bull. 
581D, 1914. 

6 Anderson, F. M., and Martin, Bruce, Neocene record in the Temblor Basin, 
California, and Neocene deposits of the San Juan District, San Luis Obispo 
County, Proc. Calif. Acad. Sci., 4th ser., vol. 4, 1914. 

~> Merriam, J. C, Tertiary vertebrate faunas of the North Coalinga Eegion 
of California, Trans. Am. Phil. Soc, vol. 22, pt. 3, 1915. 

s Merriam, J. C, New horses from the Miocene and Pliocene of California, 
Univ. Calif. Publ. Bull. Dept. Geol., vol. 9, no. 4, 1915; Eelationship of Equus to 
Pliohippus suggested by characters of a new species from the Pliocene of Cali- 
fornia, vol. 9, no. 18, 1916. 



1917] Nomland: The Etchegoin Pliocene of Middle California 195 



ern side of the San Joaquin Valley Robert Anderson and R. W. Pack 
have discussed briefly the Etchegoin and Jacalitos. 

The occurrence of the invertebrate faunas in horizons with the 
vertebrate faunas in the type Etchegoin section north of Coalinga has 
been described in a short paper by the writer."' In this publication 
Arnold and Anderson's formational names Etchegoin and Jacalitos 
and their faunal zones in the Etchegoin were retained. In a later 
paper by the writer, 11 embracing a study of the hitherto little known 
fauna of the Jacalitos formation at the type locality, the fauna of 
this formation is shown to be very closely related to the overlying 
Etchegoin. 

THE RELATION OF THE JACALITOS TO THE ETCHEGOIN 

In their report on the geology and oil resources of the Coalinga 
district Arnold and Anderson 12 state that, "the Jacalitos is likewise 
conformable to all appearances with the later Miocene (Etchegoin) 
beds which rest above it and are largely similar in composition, the 
line between these two formations being drawn somewhat arbitrarily, 
chiefly on the basis of the fossil contents." It is, however, stated in 
the same publication 13 that an unconformity between the formations 
exists, as is shown by the overlap of the Etchegoin on the Cretaceous 
in the White Creek syncline, though the beds appear conformable in 
other parts of the district. During the study of the Pliocene of the 
Coalinga district by the writer the question of the relationship of the 
Jacalitos to the Etchegoin as defined by Arnold and Anderson has 
therefore been considered of especial importance. 

The base of the Etchegoin as mapped by Arnold and Anderson 
north of Coalinga in the type section of the formation was the Gly- 
cimeris zone. It was found by the writer in attempting to extend the 
zones of Arnold and Anderson to the north that these tend to dis- 

9 Anderson, Eobert, and Pack, R. W., Geology and oil resources of the west 
border of the San Joaquin Valley north of Coalinga, California, U. S. Geol. Surv. 
Bull. 603, 1915. 

10 Nomland, J. O., The relation of the invertebrate to the vertebrate faunal 
zones of the Jacalitos and Etchegoin formations of the Coalinga District, Univ. 
Calif. Publ. Bull. Dept. Geol., vol. 9, no. 6, 1916. 

11 Nomland, J. O., Fauna from the Lower Pliocene at Jacalitos Creek and 
Waltham Canon, Fresno County, California, Univ. Calif. Publ. Bull. Dept. Geol., 
vol. 9, no. 14, 1916. 

1 2 Arnold, Ralph, and Anderson, Robert, Preliminary report on the Coalinga 
Oil District, California, U. S. Geol. Surv. Bull. 357, p. 41, 1908. 

13 Ibid., p. 47. 



196 University of California Publications in Geology [Vol. 10 



appear, and that the strata of both the Jacalitos and Etchegoin become 
unfossiliferous. Also on attempting to trace the Glycimeris zone 
southward from Coalinga it was lost within a few miles. Since no 
unconformity has been discovered near the base of this zone, either 
north or south of Coalinga or in Priest Valley, lithology and faunal 
evidence must be relied upon for age determination. 

In large areas showing exposures of the lower Etchegoin as de- 
scribed by Arnold and Anderson the sandstone has a gray or a striking 
blue color. This has frequently been considered as being due to a 
coating of sand grains by vivianite. These "vivianitic" sandstones 
have frequently been considered characteristic of the lithology of the 
lower Etchegoin, and mapping has been done on that basis. As sug- 
gested by Arnold and Anderson, this horizon is not necessarily the 
lowest occurrence of these beds. Thus in the southern part of the 
Kreyenhagen Hills the strata known by their fossil contents to be of 
Jacalitos age are of a bluish-gray color due to "vivianite." In the 
Jacalitos Hills there is no change in lithology immediately below the 
Glycimeris zone. Some distance north of the Coalinga area as mapped 
by Arnold and Anderson the sandstone supposed to be characteristic 
of the lower Etchegoin is absent. This also holds true for beds of 
equivalent age in Priest Valley. 

In the period in which the geological work of Arnold and Anderson 
was in progress the fauna of the Jacalitos was only imperfectly known. 
More recent study by the writer 14 has shown that the fauna of these 
beds is very similar to the fauna of the Etchegoin. Of the ninety- 
three species known from the Jacalitos at the present time a very large 
proportion, as shown by the accompanying table, are also found in 
the Etchegoin. The number in common with the Santa Margarita is 
shown to be small. An unconformity which occurs some distance 
above the Glycimeris zone has been described by the writer. 15 It is also 
shown that fresh-water beds occur in the lower part of the Etchegoin 
of Arnold and Anderson in the Kettleman Hills. These beds are be- 
lieved to represent the stage of the unconformity north of Coalinga. 
The faunal break is not, however, greater than is to be expected 
in a normal succession and does not appear to mark an important 
separation. 

Nomland, J. O., Fauna of the Lower Pliocene on Jacalitos Creek and 
Waltham Canon, Fresno County, California, Univ. Calif. Publ. Bull. Dept. Geol., 
vol. 9, no. 14, 1916. 

is Nomland, J. O., The relation of the invertebrate to the vertebrate faunal 
zones of the Jacalitos and Etchegoin formations of the Coalinga District, Univ. 
Calif. Publ. Bull. Dept. Geol., vol. 9, no. 6, 1916. 



1917] Nomland: The Etchegoin Pliocene of Middle California 197 



Thus no break has been found comparable to that assumed by 
Arnold and Anderson between the Etchegoin and the Jacalitos in the 
Coalinga region. On the contrary, the increase in the number of 
species and closer study of the fauna of the Jacalitos have shown a 
very decided similarity between the two, and that both are very 
different from the Santa Margarita-San Pablo. The term Jacalitos 
as a formational name must therefore be abandoned and, because of 
its close relationship to the Etchegoin, it becomes necessary to include 
the Jacalitos with that formation. In this paper the term lower 
Etchegoin will be used when referring specifically to beds equivalent 
to the Jacalitos, while upper Etchegoin will be used in reference t® 
the Etchegoin as defined by Arnold and Anderson. The upper and 
lower Etchegoin when considered together will be called the Etchegoin 
group. 



Summary of List op "Jacalitos" oe Lower Etchegoin Species 

Total number of determinable species from the "Jacalitos" 93 

Number of Recent species in the "Jacalitos" 37 

Percentage of Recent species 40 

Number of species common to the "Jacalitos" and the San Pablo-Santa 

Margarita 31 

Number of species found in the Etchegoin (of Arnold and Anderson) or in 

later deposits 68 

Number of species known only from the "Jacalitos" 19 

Number of species found in the San Pablo, Santa Margarita, and "Jacalitos" 

but not known in the Etchegoin or later formations 2 

Number of species found in the "Jacalitos," Etchegoin and later formations 

but not known in the Santa Margarita-San Pablo 37 



THE ETCHEGOIN GROUP OF MIDDLE CALIFORNIA 
Areal Distribution 

Flanking the eastern foothills of the Diablo and Temblor ranges 
is a belt of slightly consolidated deposits which usually dip at low 
angles under the alluvium of the San Joaquin Valley. In the Coalinga 
district and some distance to the north these beds have been mapped 
as the Tulare, Etchegoin, and Jacalitos formations. All these now 
appear to be probably of Pliocene age. 

In the Eastside field, comprising the northern part of the Coalinga 
district, the Etchegoin and the overlying Tulare as mapped by Arnold 
and Anderson are present. The lower, or "Jacalitos," member is 
without invertebrate fossils and the correlation with the type section 
is more difficult. South of Coalinga, in the Jacalitos Hills and in the 



198 University of California Publications in Geology [Vol.10 



Kreyenhagen Hills, the upper Etchegoin, the lower Etehegoin, and the 
Tulare show excellent exposures. In the Kettleman Hills only the 
upper Etchegoin and the Tulare are represented by outcrops. 

The Etchegoin to the north of Coalinga is not so fossiliferous as 
it is to the south, and the lithologic characters typically developed 
farther south are absent. In the northern area the separation into 
the upper and lower Etchegoin on the basis of fossil zones becomes 
impossible. It also becomes exceedingly difficult to separate the Tulare 
from the underlying formations and from the alluvium of the valley. 
Judged by lithologic characters, the lower Etchegoin appears to be 
present at Cantua Creek. Characteristic beds presumed to be sub- 
aerial found in the vicinity of Oilfields near the base of the lower 
Etchegoin also seem to be present at that creek. In these deposits 
vertebrate material has been found. About twenty miles north of 
Cantua Creek the Etchegoin and the Tulare both disappear, being 
overlapped by the alluvium of the San Joaquin Valley. 

In the mapping of the McKittrick district beds probably of the 
same age as those which had been separated into three formations 
in the Coalinga district by Arnold and Anderson were grouped by 
Arnold and Johnson 1 ' 1 as the McKittrick formation. In portions of 
this district the McKittrick group is known to be represented both 
by the upper and lower Etchegoin and the Tulare. 

Several secondary synclines are found in the Diablo Range. In 
many of these synclines, which usually extend in a northwest-southeast 
direction, are found extensive deposits of Pliocene. Among others 
may be mentioned Sunflower Valley, Waltham Creek-Priest Valley, 
White Creek Syncline, and Vallecitos Syncline. 

In the White Creek Syncline the lower part of the upper Etche- 
goin rests unconformably on the upper Cretaceous. The basin of 
deposition of the upper Etchegoin evidently had a greater extent in 
this direction than in the lower Etchegoin, as shown by this overlap. 
That a more extensive movement took place in middle Etchegoin seems 
to be suggested by the fact that in the region near Sargent, Santa 
Clara County, the upper Etchegoin rests unconformably on the Fran- 
ciscan and Monterey with no lower Etchegoin present. Along the 
upper part of Jacalitos Creek only the lower Etchegoin is found, the 
upper portion apparently having been removed by erosion. In the 
upper part of the Waltham Creek Basin are exposures of both the 

is Arnold, Ealph, and Johnson, Harry R., Preliminary report on the Mc- 
Kittriek-Sunset oil region of California, U. S. Geol. Surv. Bull. 406, 1910. 



1917] Nomland: The Etchegoin Pliocene of Middle California 199 



SAN 
FRANCISCOA 




Fig. 1. Map of California Showing Important Pliocene Localities. 1. Wild- 
cat Series at Eel Eiver. 2. Wilson 's Eanch near Santa Rosa. 3. Bolinas Bay. 
4. Merced Series, type section. 5. Purisima. 6. Pescadero. 7. Ano Nuevo Bay. 
8. Sargent and Chittenden. 9. Lonoak. 10. Cantua Creek. 11. Priest Valley. 
12. Coalinga Anticline. 13. Jacalitos Hills. 14. Kreyenhagen Hills. 15. Kettle- 
man Hills. 16. Cholame Valley. 17. Paso Eobles. 18. McKittrick. 19. Santa 
Maria. 20. Elsmere Canon. 21. Santa Paula. 22. Ventura. 23. Los Angeles. 
24. Puente Hills. 25. San Diego. 26. Carrizo Creek or Coyote Mountain. 



200 University of California Publications in Geology [Vol. 10 

... 

upper and lower divisions of the Etchegoin. Above the Etchegoin 
in that area are beds which have been correlated with the Tulare 
farther east. In Priest Valley the same relationship is found as in 
the upper part of the Waltha.ni Creek area. The lower portion of the 
Etchegoin in that region is greatly faulted, so that the different faunal 
horizons can be traced only with difficulty. At several localities, how- 
ever, fossils characteristic of the lower horizons are found. What 
corresponds to the Peeten coalingensis zone of the upper Etchegoin 
in the Jacalitos Hills can readily be distinguished in that area. 

Southeast of the San Andreas fault the Etchegoin has not been 
extensively mapped in this region. It is known, however, to be present 
about one and one-half miles southeast of Lonoak. The small fauna, 
listed in another part of this paper, indicates a probable middle Etche- 
goin age. Also about thirty miles southeast of Lonoak, on Big Sandy 
Creek, near the southeast corner of the Priest Valley Quadrangle, an 
Etchegoin fauna has been obtained. In Indian Valley of the same 
quadrangle the Pliocene is extensively developed, resting on a con- 
siderable thickness of Santa Margarita shale. The included fauna 
here indicates a lower Etchegoin age. It therefore appears probable 
that the Etchegoin may be extensively developed along the western 
slope of tlie Diablo Range. 

Relation to Adjoining Formations 
RELATION TO THE SANTA MARGARITA 

In mapping the geology of the Coalinga district by Arnold and 
Anderson the base of the "Jacalitos" (lower Etchegoin) in the north- 
ern part of the region was placed at the base of a conglomerate con- 
taining a large amount of fossil wood. This horizon is about five 
hundred feet above the uppermost fossiliferous Santa Margarita. On 
being traced northward the thickness of the Santa Margarita grad- 
ually grows less and these beds finally disappear. This apparent 
overlapping has been taken as proof of unconformity between the 
"Jacalitos" and the underlying Santa Margarita. As the writer has 
shown in another paper, 17 there are reasons for considering that this 
unconformity occurs about two hundred feet lower stratigraphically 
than the position at which it was placed by Arnold and Anderson. 
The difference in the fauna between the lower Etchegoin and the 
Santa Margarita is such that a long time must have elapsed or a 

it Univ. Calif. Publ. Bull. Dept. Geol., vol. 9, no. 6, 1916. 



1917] Nomland : The Etchegoin Pliocene of Middle California 201 



decided change of conditions taken place between the time of depo- 
sition of the two groups of deposits. That the Santa Margarita 
corresponds to a part of the San Pablo farther north more closely 
than to the Etchegoin becomes evident from a comparison of the 
faunal lists in the present paper. 

In the region south and west of Coalinga the Etchegoin overlies a 
formation decidedly different lithologically from the coarse sand- 
stone of the Santa Margarita north of that town. This formation 
consists predominantly of a compact, resistant shale which has been 
referred questionably to the Santa Margarita. In many localities, 
with excellent exposures along Waltham Creek and Kreyenhagen 
Hills, this shale appears to grade into the overlying sandstone. As 
a consequence the contact line has been placed only approximately. 
This is shown by the work of Pack and English, 18 who state: "No 
evidence of unconformity between the diatomaceous shale of the Santa 
Margarita ( ?) formation and the sandy beds of the upper Miocene 
was found, the line of contact being drawn at the horizon where the 
shale becomes sandy rather than clayey and weathers yellowish brown 
rather than purplish." The line of demarcation is placed somewhat 
lower by Arnold and Anderson, 19 according to whom: "There is a 
non-fossiliferous transition zone of alternating sandstone and shale 
beds having a thickness of several hundred feet, which may belong 
to either formation. This has been tentatively included with the 
Jacalitos in mapping, the beds to which the name Santa Margarita 
formation is applied being restricted for the present to the underlying 
shale." 

In the process of investigation of the Etchegoin an unconformity 
has been found that may mark the contact between that group and 
the Santa Margarita formation in the area west and southwest of 
Coalinga. This unconformity was first discovered at about the middle 
part of the southern boundary of sec. 7, T. 22 S, R. 15 E, M. D. B. & 
M., at an elevation of about 2100 feet. Prom this point it was traced 
in a west-northwest direction to a point at which it crosses the western 
boundary of the same section a little north of the middle of the south- 
west quarter, at an elevation of about 1600 feet. The contact con- 
tinues in the same general direction until it reaches the eastern bank 
of Jasper Creek. No attempt was made to follow the unconformity 
to the southeast beyond the point of discovery. The exposures of the 

"XL S. Geol. Surv. Bull. 581D, p. 132, 1914. 
i»U. S. Geol. Surv. Bull. 398, p. 92, 1910. 



202 



University of California Publications in Geology [Vol. 10 



beds in this part of the district are excellent. In some places a very 
sudden change was found from a fine sandy shale below to local pockets 
of conglomerate above the contact. At some localities the beds above 
contain such an abundance of shale fragments that it is in places 
difficult to distinguish the exact line of demarcation. The beds below 
could in some instances be traced to a point at which they are cut off 
at the contact or overlapped by the beds above. At one locality car- 
bonaceous material was found with what apparently was the soil of 
the old land surface. No measurable discordance in dip or strike could 
be discovered. 

RELATION TO THE TULARE 

It is the writer's opinion that in the Coalinga and adjoining areas 
tlie Etchegoin is conformable with the Tulare, and that the two were 
laid down in a period of practically continuous deposition. Struc- 
turally there appears to be no break, sedimentation having continued 
without interruption from the Etchegoin into the Tulare. The only 
recorded exception to this is reported in the Priest Valley region by 
Pack and English,- who state that "in at least part of the Priest 
Valley region the Tulare lies unconformably upon the upper Miocene 
| Etchegoin] formation just described." This relationship is appar- 
ently only local, however, as in the same publication' 21 it is stated 
that "there is no sharp change in lithology between the upper 
Miocene [Etchegoin] and the Tulare, and the line of contact has been 
drawn at the base of the beds which contain abundant pebbles of 
diatomaceous shale This gradual change in lithology and the lack 
of any structural evidence of interrupted sedimentation suggest that 
the formations are conformable here." Again the same writers 22 
state : ' ' The line between the upper Miocene and the Tulare forma- 
tion (Pliocene) is only a little more definite and has been drawn at 
the base of the beds which contain abundant pebbles of diatomaceous 
shale." In the McKittrick district 23 some distance south of the 
Coalinga area, however, the Tulare rests on the Etchegoin with angular 
unconformity. 

The deposits of the uppermost Etchegoin were laid down under 
very shallow water on land conditions, as shown by the gypsiferous 

20 U. S. Geol. Surv. Bull. 581D, p. 134, 1914. 
=i Ibid., p. 135. 
-- Ibid., p. 133. 

23 Gester, G. C, Oral communication. 



1917] Nomland: The Etchegoin Pliocene of Middle California 203 



beds and the presence of remains of land mammals in some areas. This 
is also shown by the character of the marine fauna, consisting of such 
species as Macoma nasuta, Solen sicarius, and Littorina mariana. 
Hence the transition would be only normal if the basin continued to 
be filled. The fresh-water beds with Anodonta and other fresh-water 
forms found by the writer near the base of the Etchegoin and the 
marine beds discovered by Arnold and Anderson in the Tulare indi- 
cate that only a slight oscillation was necessary to change from land 
to marine condition or the reverse during the time-interval represented 
by the two formations. 

If towards the close of the Etchegoin there was a gradual filling 
up of the Etchegoin basin and fresh-water conditions finally prevailed, 
it is evident that this could not have taken place at all points in the 
district at the same time. Therefore, if the transition is gradual and 
not represented by unconformity, the line of separation between the 
two formations would represent only approximately the same period 
of time in such widely separated areas as Priest Valley, Kettleman 
Hills, and Arroyo Honda. 

Thickness 

As already stated, the Pliocene in the region studied is of unusual 
thickness. The lower Etchegoin (" Jacalitos") as measured by Arnold 
and Anderson at Jacalitos Creek was 3800 feet thick. This figure 
should be reduced somewhat, because it includes a part of the beds 
below the unconformity described in the present paper. This would, 
however, diminish the total thickness only slightly. On Canoas Creek, 
a few miles south of Jacalitos Creek, the upper Etchegoin measured 
3600 feet. A maximum thickness of 3100 feet of Tulare, as measured 
by Arnold and Anderson, was found in the Kettleman Hills near the 
Dudley-Lemoore road. According to these measured sections, the 
aggregate thickness of the Pliocene south of Coalinga would be 10,500 
feet. This is by far the thickest Pliocene section known in America. 
Heretofore the greatest thickness known has been the Merced Series, 
a few miles south of San Francisco, California. According to Pro- 
fessor A. C. Lawson, 24 the total thickness of this series is 5834 feet. 

The question naturally suggests itself as to what were the possible 
conditions under which this great thickness of strata was deposited. 
The lower 6700 feet, or the Etchegoin group, is predominantly of 

24 Lawson, A. C, The post-Pliocene diastrophism of the coast of Southern 
California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 1, p. 147, 1893. 



204 



University of California Publications in Geology [Vol. 10" 



marine origin. On this rests with apparent conformity 3100 feet of 
Tulare, which is in large part of fluviatile or lacustrine origin. The 
lower or Etchegoin division is throughout composed of coarse sand- 
stones, clays, and numerous beds of conglomerate with a minor pro- 
portion of tuff, coal, gypsum, and limestone. The lithology, together 
with the character of the invertebrate fauna and the presence of fossil 
remains of land mammals, gives evidence of shallow-water or terrestrial 
conditions throughout the Pliocene in the Coalinga region. In order 
to have this great thickness of strata deposited at or near shore the 
basin of deposition must have been sinking concomitantly with the 
rising of the eroded area. That this was not continuous but possibly 
oscillatory is indicated by the recurrence of important conglomerates 
at various horizons. A few miles to the west, on the other slope of the 
Diablo Range, Pliocene deposits are also known to be present in con- 
siderable thickness. If we assume that erosion and deposition occurred 
over large areas we must also consider the possibility of having avail- 
able a sufficiently large land area to supply the required quantity of 
sediment. A question at once arises as to the possible location of an 
area large enough to supply by erosion during the Pliocene time sedi- 
ments sufficient to form strata two miles in thickness. If we consider 
the present mountain ranges and the Great Valley as practically per- 
manent structural features since Miocene time, the bringing of any 
material from the Sierra Nevada to be deposited in shallow water 
this far away seems out of question. One solution that may be 
offered is that the sediments were deposited only locally, and that they 
were derived from the stripping of frequently moving fault-blocks. 
On the steep sides of these blocks deposits would accumulate very 
rapidly and probably in considerable thickness. These sediments 
would, however, be only local. That such conditions existed seems 
to be suggested by comparison of the great thickness of strata south 
of Coalinga with a section about fifteen miles distant north of that 
town. In that area, near Oilfields, the Etchegoin is only 3000 feet in 
thickness. The Tulare being for the most part covered by alluvium, 
only small areas of it are exposed. 

Definite evidence for the age of the Etchegoin was first given by 
Professor J. C. Merriam, 25 who has shown that fossil land mammals 
found at the base of the lower Etchegoin (" Jacalitos") and at several 
other higher horizons represent the Pliocene. 

2 5 Merriam, J. C, Tertiary vertebrate faunas of the North Coalinga Eegion 
of California, Trans. Am. Philos. Soc, vol. 22, pt. 3, 1915. 



1917] Nomland: The Etchegoin Pliocene of Middle California 205 



It has been suggested that the Tulare may be at least in part of 
Pleistocene age. The Etchegoin and the Tulare have been much folded 
since deposition. At some localities the Tulare dips at angles of 80 
degrees. This period of folding probably occurred during the time of 
post-Pliocene diastrophic movements described by Professor A. C. 
Lawson. 26 Since some or all of the folding took place in the Kettle- 
man Hills, a region of no great relief, at least 6000 feet of strata 
have been removed by erosive agencies. In many localities the hills 
have been reduced to rounded outlines and extensive terrace deposits 
formed to unknown depth. As the exposures are excellent and show 
no evidence of faulting, it is improbable that the thickness has been 
overestimated in the section measured. 

Structure 

The dominant structural feature of the Diablo Range in the lati- 
tude of Coalinga is a broad fold plunging towards the southeast. 
Superimposed upon this are numerous small anticlines and synclines 
and in some limited areas a multitude of faults. The core of the 
Diablo Range consists essentially of both sedimentary and igneous 
rocks of the Mesozoic. The igneous rocks consist of granites and of 
various later basic igneous rocks of the Franciscan and later forma- 
tions. The sedimentaries comprise the great thickness and variety of 
clastic deposits which make up the Franciscan, Knoxville, and Chico. 
The Tertiary rocks are found flanking the main range or as remnants 
folded or faulted into the older series. 

Along the eastern slope of the Diablo Range are several anticlines 
branching away as spurs from the main fold. Of these the most 
important, in the region studied, is the Coalinga Anticline in the 
vicinity of Oilfields, about six miles north of the town of Coalinga, 
and its extension in the Kettleman Hills. Along the greater part 
of this area the Pliocene is well exposed. The structure of the 
Pliocene beds flanking the main range in the Kreyenhagen Hills 
and north of the Coalinga is in general the eastern limb of an anti- 
cline. Extending along the greater part of Jacalitos Creek, the 
upper part of the Waltham Creek basin, and then onwards through 
Priest Valley and a part of Lewis Creek is a series of small anticlines 
and synclines with infolded Etchegoin and Tulare. This region 

20 Lawson, A. C, The post-Pliocene rtiastrophism of the coast of Southern 
California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 1, 1893; The geoniorphogenv 
of the coast of Northern California, ibid., vol. 1, no. 8, 1894. 



206 University of California Publications in Geology [Vol. 10 



has also been greatly complicated by numerous faults, probably due to 
the same compressional forces. Many of these are extensive, causing 
long belts of the older rocks to appear in the midst of later formations. 
A large number of minor faults also are present, which are too local or 
too unimportant to be shown on the usual geologic map. Besides the 
faults in a general northwest-southeast direction there are numerous 
cross-faults. An interesting instance of this is found in the formation 
of Priest A 7 alley by the damming of the headwaters of Lewis Creek 
and the consequent filling with alluvium to considerable depth. The 
net result of the faulting has been to give the effect of a block of 
Pliocene having dropped down between the older formations. In the 
northwestern end, a few miles northeast of Lonoak, this fault zone 
unites with the San Andreas fault zone, of which it appears to be a 
branch. At the other end it disappears in the Jacalitos syncline a 
few miles beyond Jacalitos Creek. In other areas of the region studied 
faulting since the Pliocene has been insignificant. 

LlTHOLOGY OP THE EtCHEGOIN 

SANDSTONE, CLAY, AND CONGLOMERATE 

Due largely to the complicated distribution of the older rocks in 
this region, from which the Pliocene is mostly a derivative, the lith- 
ology of the Etchegoin varies considerably in going from one locality 
to another, having in the various areas a great resemblance to the kind 
of rock from which the sediments were derived. Also, since the 
formation is largely a shallow-water deposit in more or less local 
basins, possibly near frequently disturbed fault zones, the lithologic 
character has been still further localized. In nearly all instances the 
beds are not clearly marked off from those adjoining, but grade into 
each other. Few beds can be traced on the basis of lithology for more 
than a short distance. In the Jacalitos Hills and Priest Valley the 
region has been greatly complicated by faulting. 

South of Coalinga in the Kreyenhagen Hills the lower portion of 
the Etchegoin is composed of coarse, dark brown unfossiliferous 
sandstone. Interstratified with this is usually a minor proportion of 
yellowish-brown clay. Above this rests a great thickness of massive 
sandstone with prominent, highly indurated fossiliferous beds. At 
numerous horizons conglomerates occur or the beds may show their 
conglomeratic character only by occasional pebbles in the coarse sand- 
stone. Higher up in the formation the sandstone becomes of finer 



1917] Nomland: The Etchegoin Pliocene of Middle California 207 

grain and more argillaceous, with a more yellowish color. Above 
this, or in the lower part of the upper Etchegoin, the blue or bluish- 
gray so-called "vivianitic" sandstone usually first appears. These 
beds do not, however, appear in all parts of the district at the same 
time, but in some areas extend down into the lower Etchegoin. The 
striking blue color is particularly well shown in the Kettleman Hills. 
Somewhat higher up and continuing to the top the beds consist more 
predominantly of clays with interbedded argillaceous sandstone. 

North of Coalinga the beds which have been correlated with the 
lower Etchegoin in the Jacalitos Hills are apparently at least in part 
of non-marine origin. The basal beds in this region are composed of 
red, brown, or gray clays. In the upper part of the lower Etchegoin 
the beds are more conglomeratic, consisting largely of a coarse gray 
sandstone with interbedded pebbles. The first invertebrate fossils 
appear in the lower part of the upper Etchegoin in this region. These 
beds are composed almost entirely of ' ' vivianitic ' ' sandstone with beds 
of conglomerate. Near the middle these grade into beds consisting of 
soft yellowish clays with argillaceous sands which continue to the top. 
This has been mapped as the San Joaquin Clays by F. M. Anderson. 27 

In Priest Valley the plane of separation of the Etchegoin from 
the Santa Margarita ( ?) below has not been definitely determined. 
All the lower part of the formation is nearly devoid of diagnostic 
fossils. These beds as a whole, up to the middle of the upper Etche- 
goin, are characterized, however, by a brown sandstone of medium 
texture with only a small proportion of conglomeratic material. 
Above this the deposits grade into a predominantly fine-grained shale 
and clay, with a large amount of interbedded coal and carbonaceous 
material. From here up to the top of the Etchegoin the yellowish- 
brown or grayish, rather coarse-grained sandstone is the most evident. 

Fossils indicative of middle Etchegoin have been found on the 
west side of the Diablo Range near Lonoak, Monterey County, Cali- 
fornia. These fossils are imbedded in a thick series of beds composed 
largely of light-colored shale and volcanic ash. The rock is fine- 
grained, with only a very small proportion of coarse arenaceous 
material. 

COAL AND CAEBONACEOUS DEPOSITS 

Carbonaceous shale and beds of coal occur at various horizons of 
the Etchegoin. A seam of coal was found in what apparently are 

27 Anderson, F. M., A stratigraphic study in the Mount Diablo Eange of 
California, Proc. Calif. Acad. Sci., 3d ser., vol. 2, no. 1, 1905. 



208 University of California Publications in Geology [Vol. 10 



beds of lower Etehegoin on Frame's ranch, in the upper region of 
Jacalitos Creek. On one of the branches at the head of Waltham 
Creek thin beds of carbonaceous material were found near the middle 
of the formation. The coal deposits in the Etehegoin of Priest Valley, 
however, are by far the most important both in thickness and areal 
extent. This area has already been mapped and lithological sections 
given by Robert W. Pack and Walter A. English. 28 

As indicated by these deposits, it seems possible that the Etehegoin 
in Priest Valley and adjacent areas may have been laid down in a 
basin connecting the sea in the Great Valley with that west of the 
Diablo Range. That such connections probably existed has already 
been pointed out by F. L. Ransome, 29 who states: "The Great Valley 
was probably occupied during the whole of the Neocene by a gulf, 
connecting with the ocean by one or more sounds across the Coast 
Ranges. 

KHYOLITIC TUFFS 
Effusive rocks have been found at three horizons in the Etehegoin. 
These consist of rather persistent tuffaceous bands interstratified with 
other rocks of clastic origin. From the uniform thickness of each bed, 
the stratification planes often being distinctly visible, and from the 
intimate relation to strata containing a marine fauna, it is evident 
that these rocks were deposited in the waters of a shallow sea. The 
fine, well-sorted character indicates that the volcanic action must have 
taken place at a considerable distance from this area, although prob- 
ably in the Diablo Range, along the foothills of which the Etehegoin 
outcrops. 

On approaching Jacalitos Creek from the Stone Canon coal mine 
to the west a prominent white bed or band can be seen on the eastern 
bank several miles before reaching the creek. This is the lowest of 
the three horizons indicative of volcanic action in the Pliocene of this 
region. The bed is about twenty feet thick and is exposed for nearly 
two miles along the strike until cut off by faulting. Petrographic 
examination shows that quartz and orthoclase feldspar are the pre- 
dominant minerals in this rock. Plagioclase feldspar is also present, 
but in minor proportion. The composition therefore corresponds to 
that of a rock usually grouped under the term rhyolitic tuff. 

28 Pack, Bobert W., and English, Walter A., Geology and oil prospects in 
Waltham, Priest, Bitterwater, and Peachtree valleys, California, U. S. Geol. 
Surv. Bull. 581D, 1914. 

2» Eansome, F. L., The Great Valley of California, a criticism of the theory 
of isostasy, Univ. Calif. Publ. Bull. Dept. Geol., vol. 1, p. 386, 1896. 



1917] Nomland: The Etchegoin Pliocene of Middle California 209 



A few miles east of the bed last described, or about five miles south- 
east of Coalinga, another band outcrops on the west side of the higher 
hills. This bed resembles very closely in texture and petrographie 
characters the tuffaceous material on Jacalitos Creek. These charac- 
teristics, together with faunas of middle Etchegoin age collected above 
and below each of the two bands, indicate that they probably belong 
to the same horizon. 

Closing the period of deposition of the marine Etchegoin, or im- 
mediately before the transition of these beds into the prevailingly 
terrestrial deposits of the Tulare, volcanoes were again active in this 
region. This is shown by the large proportion of tuffaceous material 
mixed with the clays of the Mya japonica zone of the north Coalinga 
region. The tuffaceous material is of very fine texture and of rhyolitic 
composition. At one locality about one hundred feet stratigraphically 
below this horizon another bed of tuff has been found. This material 
is rather coarse-grained, as if deposited and later broken into frag- 
ments and redeposited. The tuff in this band is interstratified with 
a large proportion of quartz sand. 

The tuffaceous beds of the upper and lower Etchegoin, being 
usually very persistent, should prove of value for correlation purposes 
if found in other parts of the field. The striking characteristics of 
the beds make them readily distinguishable even at a considerable 
distance. It appears rather remarkable that they have not been found 
in the Kettleman Hills and in the Kreyenhagen Hills, a few miles to 
the south. 

GYPSUM 

At several horizons of the Pliocene in this district large quantities 
of gypsum have been found. In no instance, however, except near 
the base of the Tulare formation, are these beds known to be inter- 
stratified with the clastic series. At that horizon on the eastern flank 
of the Kettleman Hills thick gypsiferous beds occur with extremely 
fossiliferous fresh- water deposits. At several horizons in the Etche- 
goin large quantities of gypsum are found. Since these deposits of 
gypsum usually are in a very fragmentary condition, they cannot be 
assigned definitely to an origin contemporaneous with that of the beds. 
It seems improbable that large quantities of gypsum occurring exten- 
sively only at definite horizons could have filtered from other sources 
into fissures and cavities subsequent to the deposition of the Etchegoin. 

Gypsiferous beds are probably not deposited under normal marine 



210 University of California Publications in Geology [Vol. 10 



conditions. It is believed, therefore, since such conditions undoubt- 
edly frequently obtained in the Etchegoin, that the beds of gypsum 
were deposited, at least in part, in basins isolated from the ocean, in 
fresh-water lakes, or on a periodically flooded delta at the time of 
deposition of the Etchegoin. The climatic conditions under which this 
deposition took place were probably arid. 

LIMESTONE 

Along the divide between Jacalitos Creek and Salt Creek, about 
one-half mile east of Robert's ranch-house, a limestone bed outcrops. 
On megascopical examination the bed is found to be compact and 
massive in the middle, but the upper and lower portions are lami- 
nated. These laminae are very thin, being not over 2 mm. in thick- 
ness. On examination with a petrographical microscope a few minute 
grains of quartz were observed. The bed both above and below grades 
into sandstone typical of the formation. It has a thickness of about 
ten feet and is traceable about one-half mile until intersected by 
faults. "With coarse sandstone above and below containing fossils 
indicative of a shallow marine origin, the conditions necessary for 
deposition of limestone in the ocean were probably not present. The 
conclusion is therefore reached that the limestone may have been 
deposited under some such conditions as might obtain in a temporary 
lake, or in an estuary temporarily severed from the sea. 

Invertebrate Fauna 

INVEETEBEATE ZONES 

Four distinct faunal zones have been recognized in the Etchegoin. 
No fossils have been found near the base of this group. The lowest 
important fossiliferous horizon is the Chione .elsmerensis zone, in 
which C. elsmerensis English is abundant. This faunal association 
extends through several hundred feet of strata in the middle portion 
of the lower Etchegoin and is typically that of the lower Etchegoin, 
or "Jacalitos," as described by Arnold and Anderson. Several of 
the species are unknown outside of this area. The occurrence in these 
beds of C. elsmerensis English, C. fernandocnsis English and several 
other forms shows that its closest correlative is found in the lower 
Fernando near Newhall, Los Angeles County. The typical faunal 
assemblage of this zone may be found at locality 2526. Among the 
characteristic species may be mentioned Astrodapsis jacalitosensis 



1917] Nomland: The Etchegoin Pliocene of Middle California 211 



Arnold, Chione elsmerensis English, Chione fernandoensis English, 
Dosinia jacalitosana Arnold, Macoma vanvlecki Arnold, Paphia 
jacalitosana Arnold, Chrysodomus portolaensis (Arnold), Margarita 
johnsoni Arnold, and Thais kettlemanensis Arnold. 



LIST OF INVERTEBRATES FROM THE "JACALITOS" OR LOWER 
ETCHEGOIN, WITH OCCURRENCE AT OTHER HORIZONS 



ECHINODERMATA 

Astrodapsis jacalitosensis Arnold 

Astrodapsis peltoides Anderson and Martin 

Astrodapsis, n. sp. A 

Dendraster gibbsii (Remond) 

Dendraster gibbsii, n. var. B 

Dendraster eoalingensis Twitchell 

Pelecypoda 

Acila eastrensis (Hinds) 

Area trilineata Conrad 

Cardium quadrigenarium Conrad 

Chione elsmerensis English 

Chione fernandoensis English 

Cryptomya californica (Conrad) 

Cryptomya quadrata Arnold 

Cumingia californica Conrad 

Cyrena californica Gabb 

Diplodonta parilis (Conrad) 

Dosinia jacalitosana Arnold 

Glycimeris eoalingensis Arnold 

Glycimeris septentrionalis (Middendorf) .... 

Leda, cf. tephria Dall 

Macoma baltica (Linne) 

Macoma jacalitosana Arnold 

Macoma nasuta (Conrad) 

Macoma secta (Conrad) 

Macoma vanvlecki Arnold 

Metis alta (Conrad) -. 

Modiolus rectus Conrad 

Monia macroschisma (Deshayes) 

Mulinia densata Conrad 

Mytilus eoalingensis Arnold 

Mytilus kewi Nomland 

Ostrea atwoodi Gabb 

Pandora punctata Conrad 

Panope generosa (Gould) 



212 



University of California Publications in Geology [Vol. 10 



LIST OF INVERTEBRATES FEOM THE "JACALITOS' 
ETCHEGOIN — (Continued) 



OR LOWER 



Paphia jacalitosensis Arnold 

Paphia staminea (Conrad) x 

Paphia tenerrima (Carpenter) 

Pecten etehegoini wattsi Arnold 

Peeten (Hinnites) giganteus (Gray) X 

Pecten healeyi Arnold 

Peeten oweni Arnold 

Pecten terminus Arnold .... 

Periploma argentaria Conrad 

Phacoides annulatus (Reeve) X 

Phacoides richthofeni (Gabb) x 

Psamobia edentula (Gabb) 

Sanguinolaria nuttalli Conrad 

Saxidomus nuttalli Conrad x 

Sehizothaerus nuttalli Conrad x 

Semele, sp 

Siliqua lueida (Conrad) 

Solen sicarius Gould 

Spisula albaria (Conrad) x 

Spisula coalingensis (Arnold) 

Spisula hemphilli (Dall) 

Tellina bodegensis Hinds 

Thracia jacalitosensis Arnold 

Tivela trigonalis Nomland 

Yoldia cooperi Gabb x 

Zirphaea crispata (Linne) 

Gastropoda 

Astralium arnoldi Nomland 

Calliostoma coalingensis Arnold 

Calliostoma kerri Arnold 

Calyptraea filosa (Gabb) x 

Cancellaria fernandoensis tribulis, n. var 

Cancellaria crassa, n. sp 

Chrysodomus coalingensis Nomland 

Chrysodomus imperialis Dall 

Chrysodomus packardi, n. sp 

Chrysodomus portolaensis (Arnold) 

Crepidula adunca Sowerby 

Crepidula princeps Conrad x 

Fieus nodiferous Gabb x 

Fissuridea subelliptica Nomland 

Margarita johnsoni Arnold 

Murex concinna, n. sp 



c 


c 






o 






be 




i, 










a> 


a 


p 


t> 

V 


cc 


» 


X 


? 


X 




X 


X 



1917] Nomland : The Etchegoin Pliocene of Middle California 213 

LIST OF INVEBTEBKATES FBOM THE "JACALITOS" OB LOWEB 
ETCHEGOIN — (Concluded) 



ce 0-t j3 c 

Cfi OS : Ph 

Murex perangulatus Nomland 

Murex tethys, n. sp 

Nassa calif orniana (Conrad) x x 

Natica orbicularis Nomland x 

Natica recluziana Petit x x x x 

Olivella biplicata Sowerby x x 

Purpura turris Nomland x 

Sinum scopulosum (Conrad) x x x 

Thais kettlemanensis Arnolil .... x 

Thais lamellosa (Gmelin) x x 

Trophon belcheri avitum, n. var 

Trophon coalingense Arnold x 

Trophon magister Nomland x 

Turris carpenteriana (Gabb) x 

Turris coalingensis (Arnold) x 

Turris tryoniana (Gabb) x 

Turritella nova Nomland 

ClRRIPEDIA 

Balanus concavus Bronn x x 

Tamiosoma gregaria Conrad x .... x 

At a number of localities in the Jacalitos Hills and Kreyenhagen 
Hills in beds of the lower middle Etchegoin a faunal assemblage has 
been found characterized by several species unknown at other horizons 
of the formation. This fauna, known as the Turritella nova zone, is 
found typically developed at locality 2533. At this station the fauna 
consists of very large specimens of Pecten oweni Arnold, Pecten 
terminus Arnold, and Phacoides annulatus (Reeve). Well-preserved 
specimens of P. terminus may be found which have the very unusual 
width of 145 mm. Associated with these species are numerous gas- 
tropods such as Ficus nodiferous Gabb, Turris carpenteriana (Gabb), 
Turris tryoniana (Gabb), and Turritella nova Nomland. 

The most easily recognizable by its faunal assemblage and the most 
persistent in areal extent in the Etchegoin is the Pecten coalingensis 
zone. The name was first applied by Arnold to a zone occurring 
in the Kettleman Hills and in the Jacalitos Hills about 800 feet 
below the summit of the formation. Subsequent work by the writer 
has shown that this faunal association, occurring at approximately 



214 University of California Publications in Geology [Vol. 10 



the same horizon, is also found well developed in the Priest Valley, 
and that it is present north of Coalinga in beds traceable to the type 
section of the Etchegoin of Arnold and Anderson. At all localities 
where this association is found the stratigraphic range of the fauna 
appears very short, and there is no repetition at other horizons of a 
similar assemblage. A strikingly large number of the species are 
unknown outside this zone. In it are found a coral, a brachiopod, 
several species of Pecten unknown in other horizons. One of the 
most characteristic forms is Pecten etchegoini Anderson and its vari- 
eties nutteri Arnold and wattsi Arnold. It has been found that this 
species, which has been used largely for correlation in the Pliocene, 
has a very long range. This form occurs south of Coalinga from 
below the Turritella nova zone to the uppermost beds of the Etchegoin 
group, or approximately through 4000 feet of strata. Trophon ma- 
gister Nomland, formerly thought of very limited range, has been 
found in this zone. A number of the more recent forms are also 
rarely found, such as Pecten hastatus, var. hindsii Carpenter, Murex 
festivus Hinds, Trophon gracilis (Perry). 

Uppermost in the predominantly marine deposits of the Etchegoin 
and directly below the fresh-water deposits of the Tulare a faunal 
assemblage is found which has been named by Ralph Arnold the 
Mya japonica zone. It is found persistently in the Kettleman Hills 
and in the Kreyenhagen Hills. North of Coalinga a similar fauna 
has been found in a resistant band of argillaceous tuff in the outer- 
most foothills. In Priest Valley the zone does not occur and the line 
of demarcation between the Etchegoin and the Tulare is distinguished 
with difficulty. The fauna of the uppermost part of this zone is 
mainly that of shallow-water or littoral conditions. A number of 
species found immediately below the typical Mya japonica zone at 
several localities are included with the fauna of that zone in the 
accompanying list. The only species of this zone unknown in other 
horizons is Littorina mariana Arnold and its variety L. mariana, var. 
alt a Arnold. In most of the localities along this zone the so-called 
fish bulbs are found in large numbers. North of Coalinga the extinct 
horse Pliohippus proversus Merriam is found at this horizon. 

ETCHEGOIN FAUNA WEST OE THE DIABLO KANGE 
It has already been stated that the Pliocene is present on the west 
side of the Diablo Range in the latitude of Coalinga. The following 
Pliocene species have been obtained on the north bank of Whalen 



1917] Nomland: The Etchegoin Pliocene of Middle California 215 



Creek a short distance above its junction with Stone Canon and on 
Big Sandy Creek about one-half mile above its confluence with Stone 
Canon, near the southeast corner of Priest Valley Quadrangle. 

Fauna From Big Sandy Creek and Whalen Creek 

Dendraster gibbsii (Remond) Pecten healeyi Arnold 

Cardium, cf. quadrigenarium Conrad Phaeoides, sp. 

Cryptomya californiea (Conrad) Sehizothaerus nuttalli (Conrad) 

Maeoma nasuta (Conrad) Siliqua lucida (Conrad) 

Mulinia densata Conrad Solen, cf. sicarius Gould 

Ostrea, sp. Zirphaea, sp. 

Pandora punctata Conrad Calliostoma, sp. 

Paphia, sp. Chrysodomus, sp. 

Paphia, cf. tenerrima (Carpenter) Nassa califomiana (Conrad) 

Pecten estrellanus catalinae Arnold Natiea recluziana Petit 

About one and one-half miles southwest of Lonoak post-office, Priest 
Valley Quadrangle, the following fauna indicative of the middle Etche- 
goin has been found. The fossils occur in a series of beds of fine white 
ashy shale, extensively distributed in this area. 

Fauna From Lonoak 
Cryptomya calif ornica (Conrad) Fissuridea, cf. unica, n. sp. 

Ostrea atwoodi Gabb Natica, sp. 

Pecten oweni Arnold Trophon, sp. 

Pecten estrellanus Conrad, var. Tamiosoma gregaria Conrad 

Also on Vineyard Creek, San Luis Obispo County, and Indian 
V alley, Monterey County, west of the Diablo Range, Etchegoin sand- 
stone and conglomerate overlying Santa Margarita shale is extensively 
distributed. The included fauna is apparently of lower Etchegoin or 
"Jacalitos" age. 

FAUNA OF L ACUSTBINE ( ? ) BEDS 
In the north central part of the Kettleman Hills, near the middle 
of the southern part of sec. 12, T. 22 S, R. 17 E, M. D. B. & M., a bed 
containing fresh-water fossils was discovered recently by the writer. 
According to its location with respect to the upper Mulinia zone as 
mapped by Arnold and Anderson this bed comes only a short distance 
above what is called by them the base of the Etchegoin. Tbis would 
therefore come at about the same horizon as is represented by the 
unconformity recently described 30 in the region north of Coalinga. 
It appears that the time-interval marked by the unconformity of 



30 Nomland, J. O., Relation of the invertebrate to the vertebrate faunal zones 
of the Jacalitos and Etchegoin in the North Coalinga Region, California, Univ. 
Calif. Publ. Bull. Dept. Geol., vol. 9, p. 80, 1916. 



216 



University of California Publications in Geology [Vol. 1 



the northern area is indicated by fresh-water deposits in the Kettle- 
man Hills. Although fossils are very abundant in this bed, only 
the following forms could be identified: Anodonta nitida, n. sp., 
Goniobasis, sp. 

KANGE OF TEMPEEATLTEE AND DEPTH 
As shown by Ralph Arnold, the temperature of the ocean during 
Etchegoin time was probably somewhat warmer- than that of the 
Pacific Ocean in the latitude of Coalinga at the present time. A 
large number of the Etchegoin forms, with other species indicative of 
decidedly warmer water, at present live from Monterey to San Diego. 
The large specimens of Pecten terminus Arnold are indicative of warm 
conditions. Metis alto (Conrad) and Periploma argentaria Conrad 
found in the lower Etchegoin indicate warm water. No cold-water 
phases have been recognized. 

The invertebrate fauna of the Etchegoin is composed entirely of 
forms living in shallow water. At some horizons, locally, forms char- 
acteristic of brackish or even fresh water are present. Species char- 
acteristic of considerable depth have not been found. 

SEBPULA(?) BEEF 
In beds of middle Etchegoin in the Kreyenhagen Hills, on the south 
bank of Garza Creek, sec. 35, a reef outcrops which is made up almost 
entirely of tests of the genus Serpula(f) . This reef is exposed along 
the hillside for about thirty yards, with a thickness of about one and 
one-half feet. 



COMPABATIVE TABLE SHOWING STRATIGEAPHTC EELATTONSHTP OF 
FAUNAL ZONES SOUTH OF COALINGA 



Arnold. 1010 
Faunal zones 

Mya 

Pecten 
eoalingensip 

Upper Mulinia 

Glycimeris or 
Lower Mulinia 

Middle 

Big Trophon 



Nomland, 1916 
Faunal zones 

Mya 

Pecten 
coalingensi? 



Turritella nova 



Chione 
elsmerensis 



Arnold, 1910 
Formation 



Etchegoin 



Unconformity 



Jaealitos 



Nomland. 1916 
Formation 



Etchegoin 



Unconformity 



Unconformity (?) Santa 

Margarita 

Santa 
Margarita (?) 



1917] Nomland: The Etchegoin Pliocene of Middle California 217 



Vertebrate Fauna 

Perhaps the most interesting and valuable material for purposes 
of correlation found in the Etchegoin is represented by the remains 
of land mammals occurring at many widely separated localities. This 
material has been found at several horizons in both the upper and 
lower divisions of this group. 

The most important of these occurrences is about ten miles north- 
east of Coalinga. In that area in both the upper and lower Etchegoin 
vertebrates are found in zones with invertebrate zones or alternating 
with them. The vertebrates from this area have already been de- 
scribed by Professor J. C. Merriam. 31 A description of the zonal 
distribution and the occurrence of the invertebrates and vertebrates 
accompanied by faunal lists has been given in another paper by the 
writer. 32 

A short distance north of Cantua Creek remains of fossil land 
mammals have also been found. These occur in highly colored, pos- 
sibly land-laid beds which probably correspond to the lower Etchegoin 
near Oilfields. The whole Etchegoin in this area is without inverte- 
brate fossils, so that the age determination must be based on the verte- 
brate fossils, lithology, and tracing the beds into those of known age 
to the south. The fauna found in this region is comprised essentially 
of the teeth of Pliohippus coalingensis (Merriam), found also in the 
middle Etchegoin near Oilfields. 

South of Coalinga vertebrate material has been found in the Etche- 
goin in the Kreyenhagen Hills and in the Kettleman Hills. The so- 
called bulbous fish growths are found at several horizons in both the 
lower and upper Etchegoin in the Kreyenhagen Hills. Besides nu- 
merous fragments of marine vertebrates from various zones of the 
formation, a camel tooth has been found at locality 2991 with a large 
invertebrate fauna of the Pecten coalingensis zone. In the Kettleman 
Hills numerous bulbous fish growths have been found at several hori- 
zons of the upper Etchegoin. A fossil beaver tooth has been described 
by Miss Louise Kellogg 33 from this area. Fragments of a fossil horse 
have also been reported from the northern end of the Kettleman Hills. 

si Merriam, .J. C, Tertiary vertebrate faunas of the North Coalinga Region of 
California, Trans. Am. Philo's. Soc, vol. 22, pt. 3, 1915. 

32 Nomland, J. O., The relation of the invertebrate to the vertebrate faunal 
zones of the Jaealitos and Etchegoin Formations of the Coalinga District, Cali- 
fornia, Univ. Calif. Publ. Bull. Dept. Geol., vol. 9, no. C, 1916. 

33 Kellogg, Louise, A fossil beaver from the Kettleman Hills, California, 
Univ. Calif. Publ. Bull. Dept. Geol., vol. 6, no. 17, 1911. 



218 University of California Publications in Geology [Vol. 10 

FAUNAL LIST OF THE ETCHEGOIN OF THE COALINGA DISTRICT 



a c 

K o 
% SI 



Anthozoa 
Astrangia coalingensis Vaughan „. 



Vermes 



Serpula (?) 



Bryozoa 



Several species 



.t: a 



ECHINODERMATA 

Astrodapsis jacalitosensis Arnold UC 

Astrodapsis peltoides Anderson and 

Martin UC 

Astrodapsis, sp. A 

Dendraster arnoldi Twitchell 

Dendraster coalingensis Twitchell 

Dendraster gibbsii (Remond) C 

Dendraster perrini (Weaver) 

Dendraster, sp. A 

Dendraster, sp. B 

Sismondia arnoldi Twitchell 

Sismondia coalingensis Twitchell 



Brachiopoda 

Terebratalia occidentalis Dall 

Terebratalia smithi Arnold C 



UC 



UC 

c 
c 



X X .... 

x 

x x 
x 



Pelecypoda 

Acila castrensis (Hinds) R x 

Anodonta nitida, n. sp 

Area trilineata Conrad C C C C x 

Cardium eorbis (Martyn) C 

Cardium quadrigenarium Conrad R .... x 

Chama pellucida Sowerby C 

Chione elsmerensis English C x 

Chione f ernandoensis English C x 

Cryptomya californica (Conrad) C C C x 

Cryptomya quadrata Arnold C % X x 

Cumingia californica Conrad x 

Cyrena californica Gabb 

Diplodonta harfordi Anderson 

(G indicates that the species is common; R indicates that the species is rare; U indicates 
that the species is unknown outside of this horizon ; X indicates other formations in which the 
species is found. ) 



1917] Nomland: The Etchegoin Pliocene of Middle California 



219 



FAUNAL LIST OF THE ETCHEGOIN OF THE COALINGA 
DISTRICT— (Cont inued) 



••a - - c- 



Diplodonta parilis (Conrad) 

Dosinia jacalitosana Arnold 

Glycimeris coalingensis Arnold 

Glyeimeris septentrionalis (Midden- 

dorf) 

Leda, cf. taphria Dall 

Macoma baltica (Linne) 

Macoma inquinata (Deshayes) 

Macoma inquinata affinis, n. var 

Macoma jacalitosana Arnold 

Macoma nasuta (Conrad) 

Macoma secta (Conrad) 

Macoma vanvlecki Arnold 

Metis alta (Conrad) 

Modiolus fornicatus Carpenter 

Modiolus rectus Conrad 

Monia macrosehisma (Deshayes) 

Mulinia densata Conrad 

Mya japonica Jay 

Mytilus coalingensis Arnold 

Mytilus kewi Nomland — 

Ostrea atwoodi Gabb 

Ostrea lurida Carpenter 

Ostrea vespertina Conrad 

Ostrea vespertina, var. sequens Arnold 

Pandora punctata Conrad 

Panope generosa (Gould) 

Paphia jacalitosana Arnold 

Paphia staleyi (Gabb) 

Paphia staminea (Conrad) 

Paphia tenerrima (Carpenter) 

Peeten coalingensis Arnold 

Pecten egregius, n. sp 

Pecten etehegoini Anderson 

Pecten etehegoini nutteri Arnold 

Pecten etehegoini wattsi Arnold 

Pecten (Hinnites) giganteus (Gray).. 

Pecten hastatus hincisii Carpenter 

Pecten healeyi Arnold 

Peeten oweni Arnold 

Pecten proteus, n. sp 

Pecten terminus Arnold 



UR 

C 

C 

c 

c 
c 
c 



c 

UR 

c 
c 



c c c 
c 



.... R .... 

C C R 

c 

.... c .... 

c 

? c .... 

c c .... 

.... c c 

.... c c 

.... c c 

? 

c c .... 



c 

.... uc .... 

.... UR .... 

.... c .... 

.... c .... 

.... C R 



R 



uc 



c 



ft 3 
ftw 



„ 3 



(C indicates that the species is common; B indicates that the species is rare; U indicates 
that the spsuss is unknown outside of this henzon X indicates oth:r formations in wlii;h the 
species is found.) 



220 



University of California Publications in Geology [Vol. 10 



FAUNAL LIST OF THE ETCHEGOIN OF THE COALINGA 
DISTRICT — (Continued) 



0) 




Eh 

0) N 

."ti ci 


D CO 


*j o 







Periploma argentaria Conrad ... . 

Petricola carditoides (Conrad) 

Phacoides annulatus (Reeve) /'„.. 

Phacoides richthofeni (Gabb) R 

Phacoides sanctaecrusis Arnold 

Pholadidea ovoidea Gould 

Placunanomia californica Arnold 

Psamobia edentula (Gabb) 

Psephis lordi (Baird) 

Sanguinolai ia nuttalli Conrad 

Saxidomus nuttalli Conrad 

Schizothaerus nuttalli Conrad C 

Seniele fausta, n. sp 

Semele rubropicta Dall 

Siliqua lucida (Conrad) C 

Solen sicarius Gould C 

Spisula albaria (Conrad) 

Spisula coalingensis (Arnold) 

Spisula falcata (Gould) 

Spisula hemphilli (Dall) C 

Tellina bo<legensis Hinds C 

Tivela trigonalis Nomland 

Thracia formosa, n. sp 

Thracia jaealitosana Arnold 

Transennella californica Arnold 

Yoldia cooperi Gabb 

Zirphaea crispata (Linne) 



R 

C 

UR 
R 



p. 3 



X X 
X X 
X .... 



X 
X 

X X 

X 
X 

X X 
X .... 

X 
X 

X X 



Gastropoda 



Astralium arnoldi Nomland 

Calliostoma coalingensis Arnold C 

Calliostoma etchegoinensis Nomland 

Calliostoma kerri Arnold 

Calyptraea filosa (Gabb) C 

Cancellaria crassa, n. sp 

Cancellaria fernandoensis tribulis, n. 

var 

Cancellaria rapa, n. sp 

Cancellaria tritonidea Gabb 

Chrysodomus coalingensis Nomland 

Chrysodomus imperialis Dall R 



C 
UR 



R 



(C indicates that the species is common; R indicates that the species is rare; D indicates 
that the species is unknown outside of this horizon: X indicates other formations in which the 
species is found.) 



1917] Nomland: The Etchegoin Pliocene of Middle California 221 



FAUNAL LIST OF THE ETCHEGOIN OF THE COAL1NGA 
DISTRICT — (Continued) 



a^^o^^x z g - - T 

ii n . ~ . . a. .5 

B 3 is g S io « S S3 £ ?" Z i* S2 S £ 
■2 g C S o g ? g S3 »S "tj £ * 

o £« fM S J j s Ph j 

Chrysodomus packardi, n. sp 

Chrysodomus portolaensis (Arnold) C C x .... x x 

Columbella (Astyris) richthofeni Gabb x x x 

Crepidula adunca Sowerby E 

Crepidula princeps Conrad C .... C C x x x x .... 

Drillia mercedensia Martin x x 

Epitonium varieostata Stearns C 

Fieus nodiferous Gabb C C x 

Fissuridea subelliptica Nomland UR 

Fissuridea uniea, n. sp UC 

Goniobasis kettlemanensis Arnold R 

Littorina mariana Arnold UC 

Littorina mariana alta Arnold UC 

Margarita johnsoni Arnold C ? 

Murex coneinna, n. sp 

Murex festivus Hinds R 

Murex perangulatus Nomland 

Murex tethys, n. sp C R 

Nassa ealiforniana (Conrad) C C C 

Natiea convexa Nomland 

Natiea orbicularis Nomland C C R x 

Natiea recluziana Petit C C C C x x 

Natiea reeluziana alta Dall 

Olivella biplicata Sowerby C 

Olivella pedroana (Conrad) 

Pisania fortis angulata Arnold x .... 

Purpura turris Nomland 

Sinum seopulosum (Conrad) ? x .... 

Tegula (Chlorostoina) pulcella, n. sp UR 

Thais kettlemanensis Arnold C C x 

Thais lamellosa (Gmelin) C C C C 

Trophon beleheri avitum, n. var UR 

Trophon eoalingense Arnold R ? ? 

Trophon gracilis (Perry) R 

Trophon inagister Nomland C C R 

Turris carpenteriana (Gabb) C 

Turris carpenteriana fernandoana 

Arnold R .... x .... 

Turris eoalingensis (Arnold) R C x .... 

Turris tryoniana (Gabb) C 

Turritella nova Nomland UC 

Turritella vanvleeki Arnold 





X 




X 


x 


X 


X 










X 


X 




X 


X 


X 




X 


X 


X 


X 


y 


X 






X 





(C indicates that the species is common; R indicates that the species is rare; U indicates 
that the species is unknown outside of this horizon ; X indicates other formations in which the 
species is found.) 



222 University of California Publications in Geology [Vol. 10 



FAUNAL LIST OF THE ETCHEG01N OF THE COALINGA 
DISTRICT — (Concluded) 

| a 3 v o 

- S rt 5 c § O 10 += - as 

^ ^ ^ S ° « a 5 = 7 
■2S SS » ^ |S 'E ^ g 

J3 ^ Sc £'S Ofe =02 O-CC = o g aj 

o h h g j ti PMhJ W 

Crustacea 

Balanus coneavus Bronn C C x 

Cancer fissus Rathbun 

Loxorhynehus grandis Stimpson 

Tamiosoma gregaria Conrad C * 

Pisces 

Careharodon arnoldi Jordan 

Fish, bulbous growths : 

Reptilia 

Testudo(f), sp 

Mammalia 

Camelops or Pliauchenia, sp 

Castor ealifornicus Kellogg 

Cervus or Odocoileus, sp : 

Mastodon 

Neohipparion molle Merriam 

Pliohippus coalingensis (Merriam) 

Pliohippus proversus Merriam 

Pliohippus, cf. tejonensis (Merriam) 

Proeamelus( ?), sp 

Tayassu or Mylohyus 

(C indicates that the species is common; R indicates that the species is rare; U indicates 
that the species is unknown outside of this horizon ; X indicates other formations in which the 
species is found.) 



Summary of Etchegoin Invertebrate Faunal List 

Anthozoa 1 

Echinodermata 11 

Braehiopoda 2 

Pelecypoda 80 

Gastropoda 53 

Crustacea 4 

Total number of determinable Etchegoin invertebrate species 149 

Number of Recent molluscan species in the Etchegoin 50 

Percentage of Recent molluscan species 39 

Percentage of Recent species in gastropod fauna of Etchegoin 21 

Number of species known only from the Etchegoin of Coalinga 42 

Total number of species reported from the lower Fernando near Newhall .... 60 
Number of species common to the Etchegoin and the lower Fernando near 

Newhall 27 

Total number of species reported from the lower Pliocene near Sargent 38 

Number of species common to the Etchegoin and the lower Pliocene beds 

near Sargent 30 



1917] Nomland: The Etchegoin Pliocene of Middle California 223 

Total number of species reported from the upper Pliocene near Sargent ... . 45 
Number of species common to the Etchegoin and the upper Pliocene beds 

near Sargent 26 

Total number of species reported from the Purisima 59 

Number of species common to the Etchegoin and Purisima 32 

Total number of species reported from the lower Merced 41 

Number of species common to the Etchegoin and lower Merced 25 



Age and Correlation op the Etchegoin 
histoey of coeeelation 

The name Etchegoin Beds, used by F. M. Anderson 34 in the first 
descriptions of the formation, included only the upper Etchegoin as 
used by the writer. These beds were thought by Anderson to be of 
approximately the same age as the San Pablo formation, this corre- 
lation being based chiefly on lithology. The Etchegoin Beds and the 
San Pablo were both included in the Pliocene. The thick series of 
strata immediately underlying the Etchegoin Beds, including the 
Jaealitos, Santa Margarita and a portion of the Vaqueros as later 
mapped by Ralph Arnold and Robert Anderson, were grouped by 
P. M. Anderson as the Coalinga Beds. These beds were believed to 
be of upper Miocene age and to be separated from the Etchegoin Beds 
by an unconformity. 

The Jaealitos and Etchegoin formations as mapped by Arnold and 
Anderson 35 were held to represent the middle and upper Miocene. 
The Etchegoin was considered equivalent to a considerable part of 
the San Pablo. The Etchegoin was also believed to be equivalent to, 
or possibly older than, the Purisima and was thought to be earlier 
than the Merced. 

According to Professor J. P. Smith, 38 "The lower division of the 
upper Miocene consists of the San Pablo-Santa Margarita-Jacalitos 
faunas, which are a unit, or nearly so . . . the Jaealitos being merely 
the upper division of the Santa Margarita, and both together being 

3-* Anderson, F. M., A stratigraphic study in the Mount Diablo Eange of 
California, Proc. Calif. Acad. Sci., 3d ser., vol. 2, no. 1, 1905; A further study 
in the Mount Diablo Eange of California, Proc. Calif. Acad. Sci., 4th ser., vol. 3, 
1908. 

35 Arnold, Ealph, and Anderson, Eobert, Preliminary report on the Coalinga 
Oil District, U. S. Geol. Surv. Bull. 357, 1908; Arnold, 'Ealph, Palaeontology of 
the Coalinga District, Fresno and Kings counties, California, U. S. Geol. Surv. 
Bull. 396, 1909; Arnold, Ealph, and Anderson, Eobert, Geology and oil resources 
of the Coalinga District, California, U. S. Geol. Surv. Bull. 398, 1910. 

36 Smith, J. P., Geologic range of Miocene invertebrate fossils of California, 
Proc. Calif. Acad. Sci., 4th ser., vol. 3, pp. 161-182, 1912. 



224 University of California Publications in Geology [Vol. 10 



the approximate equivalent of the San Pablo." The Etchegoin as 
recognized by Arnold and Anderson was placed in the upper Miocene. 
The Purisima was believed to be higher than the Etchegoin and of 
Pliocene age. 

In a short paper by W. A. English 37 on the Fernando near New- 
hall, Los Angeles County, California, the conclusion was arrived at that 
the lower Fernando probably does not differ greatly in age from the 
Etchegoin of Arnold and Anderson. 

In a recent paper by R. W. Pack and W. A. English 38 on the region 
west of the Coalinga district little attempt was made at a faunal study 
of the Etchegoin. The Jacalitos and Etchegoin were grouped as upper 
Miocene. According to these writers, "the Jacalitos and Etchegoin 
formations are believed to be in the main younger than the true Santa 
Margarita, although the fauna contained in the lower part of what is 
mapped as upper Miocene in Waltham Canon shows a close similarity 
to that of the true Santa Margarita." 

The Jacalitos and Etchegoin are grouped by Robert Anderson and 
R. W. Pack 39 as upper Miocene, or possibly in part lower Pliocene, 
and are thought to be of the same age as the San Pablo. 

By finding remains of land mammals with the marine deposits in 
the Etchegoin it becomes possible to correlate this group definitely 
also with distant terrestrial deposits containing only remains of land 
vertebrates. The mammalian remains have been studied by Professor 
J. C. Merriam, 40 who places both the Etchegoin and Jacalitos of 
Arnold and Anderson in the Pliocene. The Santa Margarita-San 
Pablo is placed in the upper Miocene. 

The study of the San Pablo of middle California by Dr. B. L. 
Clark apparently shows that this group is of upper Miocene age. The 
Santa Margarita is considered by him equivalent to the upper part of 
the San Pablo, while the Etchegoin is recognized as Pliocene. Dr. 
Clark states that it is his opinion that the Jacalitos is probably younger 
than the San Pablo. 

In a recent publication on the Pliocene of California by Bruce 

3 7 English, W. A., The Fernando Group near Newhall, California, Univ. Calif. 
Publ. Bull. Dept. Geol., vol. 8, no. 8, 1914. 

38 Pack, E. W., and English, W. A., Geology and oil prospects in Waltham, 
Priest, Bitterwater, and Peachtree valleys, California, IT. S. Geol. Surv. Bull. 
581D, 1914. 

39 Anderson, Eobert, and Pack, B. W., Geology and oil resources of the west 
border of the San Joaquin Valley north of Coalinga, California, U. S. Geol. Surv. 
Bull. 603, 1915. 

40 Merriam, J. C, Tertiary vertebrate faunas of the North Coalinga Begion 
of California, Trans. Am. Philos. Soc, vol. 22, pt. 3, 1915. 



1917] Nomland: The Etchegoin Pliocene of Middle California 225 



Martin 41 the lower Pliocene beds found near Sargent, called San Pablo 
by Jones, are referred to the same horizon as the Etchegoin. Martin 
also states that a portion of the Purisima is probably equivalent to a 
portion of the Etchegoin of Arnold and Anderson. 

AGE DETERMINATION 

As will be seen by a comparison of the faunal lists, the lower 
Etchegoin has a greater percentage of Recent species than the upper 
division or than the formation as a whole. According to the usual 
custom of calculating by the Lyell percentage method, the lower 
Etchegoin should therefore be placed later in the geologic time-scale 
than the upper Etchegoin. In this instance we know by undoubted 
stratigraphic evidence that this is not a fact. We know also that 
during the deposition of approximately 7000 feet of Pliocene a con- 
siderable faunal evolution must have occurred. 

That the percentage method has only a very limited degree of 
accuracy was shown by Dr. W. H. Dall 42 nearly twenty-five years ago 
in the following statements : 

There is no doubt that Lyell 's hypothesis has been of great use in settling 
early Neozoic nomenclature, and has generally hitherto been applied in a manner 
to which little exception could be taken. But the old conception of the mathe- 
matical individuality of species has passed away, never to return, and the 
numerical estimates based upon it are no longer practicable in the absence of 
any method of determining the personal equation of different palaeontologists 
in their estimates of what constitutes a species. 

The classification retaining these names is no longer numerical, but strati- 
graphic and developmental, and the formations classified under a given name 
are, for the writer at least, not necessarily synchronous, except where strati- 
graphically continuous, or synchronic only in a very wide and general sense. 

It is believed that American geologists are well agreed that the minor sub- 
divisions of the systems cannot in America at present be subjected to any rigid 
parallelism with the minor subdivisions of other lands, and that the difficulty of 
correlation increases with the differences of latitude and distance. Concurring 
in this opinion, theoretically and practically, no attempt at such correlation has 
been attempted by the writer within the geological limits assigned to him. 

It appears, therefore, that the Lyell percentage method can be 
applied only to the larger divisions and only in a very general way. 
The very fine distinctions which have frequently been made as to the 
relative age of many of the California Tertiary formations based on 

« Martin, Bruce, The Pliocene of Middle and Northern California, Univ. 
Calif. Publ. Bull. Dept. Geol., vol. 9, no. 15, 1916. 

« Dall, W. H., Correlation papers, Neocene, U. S. Geol. Surv. Bull. 84, p. 179, 
1892. 



226 



University of California Publications in Geology [Vol. 10 



the percentage method are of little value. The finer age determina- 
tions will probably have to be made by comparing highly specialized 
forms from the various horizons and by a direct comparison with 
faunal zones, the position of which lias already been found in a section 
of known stratigraphic sequence. 

In regard to the Pliocene beds of Florida Dr. Dall 43 states : 

In the discussion of these tables, if we adopt the old-fashioned method, it 
appears that, throwing all doubtful species into the category of extinct forms, 
we have from the Waccamaw beds 125 out of 180 species still living, or about 
70 per cent; while from the Crotan beds we have 80 out of 96 species repre- 
sented in the recent fauna, or over 83 per cent. By this method the Pliocene 
character of the beds is obvious, according to the numerical rule. 

Also for the Miocene of Maryland the same writer 44 shows that the 
number of Recent species ranges from 8.5 to 20 per cent. It will thus 
be seen that the percentage of Recent species in the Etchegoin, 39+ 
per cent, falls between these two series of figures. 

The Etchegoin of the Coalinga district rests unconformably on the 
Santa Margarita, which, as shown by Dr. B. L. Clark, 45 is probably 
of the same age as the upper part of the San Pablo. The percentage 
of Recent species in the San Pablo is 23+. According to Dr. Clark, 
this would place the San Pablo in the upper Miocene or possibly lower 
Pliocene. 

In regard to the mammalian remains found in the Etchegoin 
Professor J. C. Merriam 40 states: "The time-relations of the Jaca- 
litos [lower Etchegoin] vertebrates to the faunas of the Great Basin 
Province are not entirely clear, but the closest relationships seem to 
be with the lower Pliocene." 

CORRELATION WITH OTHER PLIOCENE FORMATIONS 
On comparison of the Etchegoin in the region studied by the writer 

with other Pliocene faunas of California it is found that at no other 

locality do we find a section that corresponds to the whole Etchegoin 

studied at Coalinga. 

The fauna most closely related to the lower Etchegoin is found in 

the lower Fernando near Newhall, Los Angeles County. Of the sixty 

« Dall, W. H., Tertiary mollusks of Florida, Trans. Wagner Inst. Sci., vol. 3, 
pt. 2, p. 215, 1892. 

44 Dall, W. H., The relations of the Miocene of Maryland to that of other 
regions and to the Recent fauna, Md. Geol. Surv., Miocene, p. 147, 1904. 

« Clark, B. L., Fauna of the San Pablo Group of Middle California. Univ. 
Calif. Publ. Bull. Dept. Geol., vol. 8, no. 22, 1915. 

40 Merriam, J. C, Tertiary vertebrate faunas of the North Coalinga Region, 
Trans. Am. Philos. Soc, vol. 22, pt. 3, p. 30, 1915. 



1917] Nomland: The Etchegoin Pliocene of Middle California 227 

species listed from that locality, twenty-six are also found in the 
Etchegoin of Coalinga. Considering the distance by which these 
localities are separated, a striking resemblance is evident. Among 
the species strongly suggesting this close relationship may be men- 
tioned Terebratalia smithi Arnold, Pecten healeyi Arnold, Pecten 
oweni Arnold. "With these forms occur also several species unknown 
except from the lower Fernando near Newhall and from the Etchegoin 
near Coalinga; these are Chione elsmerensis English, Chione fernan- 
doensis English, Turris coaling ensis Arnold, and Dosinia jacaUtosana 
Arnold. Good specimens of Pecten estrellanus catalinae Arnold, listed 
by Arnold from the lower Fernando near Newhall, have been obtained 
by the writer from beds that appear to represent middle Etchegoin 
at Big Sandy Creek on the west side of the Diablo Range. 

The fauna most closely related to the upper Etchegoin is undoubt- 
edly that listed from the lower Pliocene beds at Sargent. Of the 
thirty-eight species listed from that formation at Sargent, thirty are 
found in the upper Etchegoin at Coalinga. The species in common 
include Dendraster gibbsii (Remond), Pecten etchegoini Anderson and 
its varieties nutteri Arnold and watt si Arnold. 

As will be seen by the Etchegoin fauna as summarized in this 
paper, nearly one-half of the species reported from the Purisima and 
more than one-half of the species reported from the lower Merced are 
found in the Etchegoin near Coalinga. The characteristic species 
common to the Merced, and especially those common to the Purisima, 
seem to be such as are confined to the middle and upper Etchegoin. 
It seems probable, however, that the Etchegoin and Merced basins 
represent different faunal provinces. In the Merced are included 
several species indicating a closer relationship to the northern forms 
than the warm water Etchegoin fauna. 

Summary 

1. The accumulation of over 10,000 feet of Pliocene has occurred 
under shallow marine or terrestrial conditions. 

2. In the period in which this accumulation took place the floor of 
the basin of deposition was several times raised locally above sea-level. 
After the prevailingly terrestrial conditions had begun marine depo- 
sition occurred for brief periods. 

3. Diastrophic movements of great magnitude occurred in post- 
Pliocene time in the Coalinga region. 



228 University of California Publications in Geology [Vol. 10 



4. The strata above the Santa Margarita and below the Tulare 
belong to one period of deposition. 

5. The Santa Margarita-San Pablo fauna is distinctly different 
from that of the Etchegoin. 

6. As shown by both invertebrates and the vertebrates, the whole 
Etchegoin is of Pliocene age. 

7. An unconformity occurring in the lower portion of what has 
been mapped as the Etchegoin southeast of Coalinga is probably 
the line of division of the Etchegoin from the underlying Santa 
Margarita. 

8. An unconformity occurring in the Etchegoin north of Coalinga 
above the "Glycimeris zone" is probably of only local importance. 

9. Four distinct faunal zones have been recognized in the Etche- 
goin. 

10. The lower Etchegoin is most closely related to the lower Fer- 
nando near Newhall, while the upper Etchegoin is most closely related 
to the lower part of the Pliocene beds at Sargent. 



Description of Etchegoin Invertebrate Localities 

Out of about two hundred fossil localities in the Etchegoin near 
Coalinga and in the adjoining regions the following have been selected 
as showing typically the faunal association of the Etchegoin. 

All townships and ranges referred to Mount Diablo Base Line and 
Meridian. 

2089. Middle of eastern boundary of NW % of NW % Sec. 19, T. 19 S, R. 16 E. 

Mya zone, uppermost Etchegoin. 
2091. On west slope of 1100-foot hill near NE corner of NW % Sec. 26, T. 19 S, 

R. 15 E. Vertebrate and invertebrate locality, lowest invertebrate 

fossiliferous zone. 

2093. In creek bed immediately east of 900-foot hill, SE corner of NW % of 
NW % Sec. 13, T. 19 S, R. 15 E. Lowest invertebrate fossiliferous 
zone, type section of the formation as used by Arnold and Anderson. 

2096. Near middle of eastern boundary of SW % of SE % Sec. 35, T. 19 S, 
R. 15 E. In this area the lowest invertebrate fossilferous zone. 

2104. Middle of northern boundary of NE % Sec. 12, T. 21 S, R. 14 E. Upper 
Etchegoin. 

2110. Middle of southern boundary of Sec. 1, T. 21 S, R. 14 E. Upper middle 
Etchegoin. 

2376. Middle of southern boundary of SE % of SW % Sec. 6, T. 20 S, R. 16 E. 
Pecten coalingensis zone. 



1917] Nomland: The Etchegoin Pliocene of Middle California 229 



2377. Center of NW % of SE % Sec. 34, T. 19 S, E. 15 E. Lowest invertebrate 
fossiliferous zone. 

2520. Near center of SE % of NW % Sec. 24, T. 21 S, R. 14 E. About 200 
yards east of Alealde-Jacalitos Ranch road. Chione elsmerensis zone. 

2523. Center of SE % of SE % Sec. 27, T. 21 S, R. 14 E. Short distance west 
of most southern curve of Alealde-Jacalitos Ranch road around Curry 
Mountain, about 15 yards above road. Probably Turritella nova zone. 

2526. At junction of Jaealitos Creek and Jasper Creek, near SW corner of 
See. 6, T. 22 S, R. 15 E. Chione elsmerensis zone. One of typical 
' ' Jaealitos ' ' localities. 

2532. Near top of small ridge on old Coalinga-Stone Canon road, SE corner of 

NW \i of NW % See. 21, T. 21 S, R. 14 E. Chione elsmerensis zone. 

2533. Middle of southern boundary of NW % of NE % Sec. 29, T. 21 S, R. 14 E, 

on north bank of Waltham Creek. Turritella nova zone. 

2534. About 100 yards south of B. M. 1699, on old Coalinga-Stone Canon road, 

near middle of western boundary of Sec. 31, T. 21 S, R. 14 E. Chione 
elsmerensis zone. 

2535. About 20 yards stratigraphically above 2534. 

2616. Near SW corner of NW % of SE % Sec. 3, T. 22 S, R. 14 E. Probably 
Chione elsmerensis zone. 

2619. On divide at SE corner of NE % of SE % Sec. 32, T. 21 S, R. 14 E. 
Lower middle Etchegoin. 

2622. About 20 yards SE of B. M. 1699, See. 31, T. 21 S, R. 14 E. Chione els- 
merensis zone. 

2643. South middle part of NE % of NW % Sec. 29, T. 21 S, R. 14 E. Chione 
elsmerensis zone. 

2649. Near center of NW % of SE % Sec. 19, T. 21 S, R. 14 E. Middle 

Etchegoin. 

2650. At NE corner of SW Vi of SE *4 Sec. 19, T 21 S, R. 14 E. Middle 

Etchegoin. 

2663. East central part of NE % of NW % Sec. 34, T. 21 S, R. 14 E. Probably 

Chione elsmerensis zone. 

2664. In saddle of ridge, NE corner of NW % Sec. 34. T. 21 S, R. 14 E. Turri- 

tella nova zone. 

2669. SW corner of SE % of NW % Sec. 34, T. 21 S, R. 14 E. Undifferentiated 

Etchegoin. 

2670. On south side of 1600-foot hill near north central part of SW % of NW 
% Sec. 34, T. 21, R. 14 E. About middle Etchegoin. 

2672. Near center of SE % of NW % Sec. 34, T. 21 S, R. 14 E. Chione elsme- 
rensis zone. 

2679. Middle of northern boundary of SE % of NE 14 Sec. 7, T. 22 S, R. 15 E. 

Resistant strata containing Astrodapsis in abundance. Chione elsme- 
rensis zone. 

2680. On ridge, south central part of NW % of NW % Sec. 8, T. 22 S, R. 15 E. 

Turritella nova zone. 

2684. Near middle of SE % of NE % Sec. 12, T. 22 S, R. 14 E. Undifferenti- 
ated lower Etchegoin. 

2693. On ridge extending from 1910-foot hill near NE corner of SW % of NE 
% Sec. 24, T. 21 S, R. 14 E. Lower middle Etchegoin. 

2958. Middle of eastern boundary of NE % of NE % Sec. 7, T. 23 S, R. 17 E. 

Immediately below lowest "vivianitic" sandstone. Turritella nova 
zone. 



230 



University of California Publications in Geology [Vol. 10 



2962. Near SE corner of NW Vi Sec. 7, T. 23 S, E. 17 E. Hard stratum on bank 
of creek. Chione elsmerensis zone. 

2964. NE corner of NW % Sec. 7, T. 23 S, E. 17 E. Probably Turritella nova 

zone. 

2965. SE corner of NE % Sec. 36, T. 22 S, E. 16 E. Immediately north of road. 

Mya japonica zone. 

2966. Near SW corner of NE % Sec. 35, T. 22 S, E. 16 E. Upper middle 

Etehegoin. 

2971. Near center of SW % Sec. 9, T. 23 S, E. 17 E. Probably Turritella nova 
zone 

2973. At SE corner of Sec. 8, T. 23 S, E. 17 E. On small branch of creek. 

Lowest fossiliferous zone in this region. 

2974. South central part of SE % of SW % Sec. 8, T. 22 S, E. 16 E. On small 

creek. Pecten coalingensis zone. 

2975. About 100 feet above 2974. Pecten coalingensis zone. 

2976. Near NE corner of NW 14 Sec. 24, T. 22 S, E. 15 E, at elevation of about 

1500 feet. Chione elsmerensis zone. 

2977. South central part of SW % Sec. 13, T. 22 S, E. 15 E. Middle Etehegoin. 
2982. Sec. 8, T. 22 S, E, 16 E. On ridge east of Zapato Creek, about % mile 

SE of Adolph Kreyenhagen 's home. Pecten coalingensis zone. 

2985. Near SW corner of SE % Sec. 20, T. 22 S, E. 16 E. Middle Etehegoin. 

2986. About 50 feet stratigraphically higher than 2985. 

2987. West central part of Sec. 20, T. 22 S, E. 16 E. Middle Etehegoin. 

2988. About 50 yards SE of 2987, about same horizon. 

2991. Near center of SE % Sec. 17, T. 22 S, E. 16 E. On top of ridge south of 

road. Pecten coalingensis zone. 
3001. On bank of creek near center of NW % of NW % Sec. 14, T. 20 S, E. 12 E. 

Pecten coalingensis zone. 

3003. On bank of creek near SW corner of Sec. 10, T. 20 S, E. 12 E. Pecten 

coalengensis zone. 

3004. West central portion of Sec. 10, T. 20 S, E. 12 E. Hard stratum on creek 

bank, short distance above coal. 

3005. At confluence of two small creeks near center of NE % of NE % Sec. 9, 

T. 20 S, E. 12 E. A few hundred feet below coal. Middle Etehegoin. 
3007. Immediately above pipe line near center of SW % of NW % See. 26, 
T. 20 S, E. 12 E. Middle Etehegoin. 

3010. Near central portion of Sec. 35, T. 20 S, E. 12 E. Middle Etehegoin. 

3011. About 600 yards south of 3010. Probably Chione elsmerensis zone. 
3013. On creek near NE corner of SW % of NE % Sec. 23, T. 20 S, E. 12 E. 

Probably float from middle Etehegoin. 
3016. SE corner of NE % of NE % Sec. 14, T. 20 S, E. 12 E, on bank of creek. 
Middle Etehegoin. 

3020. On small branch of creek, near SE corner of Sec. 27, T. 20 S, E. 12 E. 
Middle Etehegoin. 



ANTHOZi 
Astrangia coalingensis 1 
ECHINODEE, 

Astrodapsis jaealitosensi 
Astrodapsis peltoides Ai 

Astrodapsis, sp. A 

Dendraster arnoldi Twi 
Dendraster coalingensis 
Dendraster gibbsii (Rei 
Dendraster perrini (W 
Dendraster, sp. A 



AOSOHTR A 

isiigusT eieasgoilaoa 



1917] Nomland: The Etchegoin Pliocene of Middle California 231 



DESCRIPTION OF SPECIES 
ANODONTA NITIDA, n. sp. 
Plate 9, figure 2 
Type specimen no. 11091, Univ. Calif. Coll. Invert. Palae. 

Shell of moderate size, equivalve, thin, rather compressed, ventral 
part of sides of posterior end flattened, with subpentagonal, angular 
outline. Beaks low, inconspicuous. Anterior region about one-fourth 
of length of shell ; anterior dorsal margin rounded, with slightly in- 
creased convexity a short distance in front of beaks ; anterior extremity 
rather sharply angular ; posterior extremity slightly truncated ; pos- 
terior dorsal margin to upper angle of truncation nearly two-thirds 
of distance from beak to posterior end ; from this angle to lower angle 
of truncation margin is slightly concave ; posterior ventral margin has 
increased convexity slightly more than one-third of length of shell 
from posterior end. Surface ornamented by numerous wide concentric 
ridges. Height, 38 mm. ; length, 54 mm. 

This species may be recognized by compressed form, inconspicuous 
anteriorly located beaks, angular outline, and flattened posterior ven- 
tral portion of sides. 

Occurrence. — At locality 2999, on ridge a little east of middle of 
southern boundary of sec. 12, T. 22 S, R, 17 E, M. D. B. & M., northern 
end of Kettleman Hills. At the type locality this species occurs with 
Goniobasis, sp., in fresh-water horizon at or near the base of the upper 
Etchegoin. 

PECTEN EGEEGIUS, n. sp. 
Plate 6, figures 3, 3a, 3b 
Type specimen no. 11090, Univ. Calif. Coll. Invert. Palae. 
Shell equilateral, equivalve, thin, rather compressed ; with smooth, 
regularly rounded base. Dorsal margins long; umbonal angle about 
70 degrees. Right valve with about 22-23 moderately strong, rounded 
ribs; in each interspace there is one small, often invisible, rounded 
riblet; anterior ear long, arcuate in front, ornamented above byssal 
notch by about six distinct, radiating ridges and numerous incremental 
lines; byssal notch well defined; posterior ear very small, sculptured 
by low radiating ridges and inconspicuous incremental lines. Left 
valve with about 22 subequal ribs, which are not so prominent as those 
of the right valve, but with auxiliary riblets more distinct ; anterior 
ear large, with sculpture consisting of faint incremental lines and 
about twelve radiating ridges; posterior ear similar to that on the 



232 University of California Publications in Geology [Vol. 10 



right valve. Dimensions of type, which is a rather small specimen: 
height, 31 mm. ; width, 24 mm. ; width of hinge, 13 mm. 

Occurrence. — At localities 2991, 2975, Pecten coalingensis zone, 
upper Etchegoin Pliocene. 

PECTEN PROTEUS, n. sp. 
Plate 6, figures 2, 2a, 2b, 2c 
Type specimen no. 11089, Univ. Calif. Coll. Invert. Palae. 

Pecten deserti Conrad. Arnold, Ealph, U. S. Geol. Surv. Bull. 396, p. 76, 

pi. 26, figs. 3, 4, 1909. 
Pecten deserti Conrad. Arnold, Ralph, and Anderson, Robert, U. S. Geol. 

Surv. Bull. 398, pi. 48, figs. 3, 4, 1910. 

Shell thin, equilateral, equivalve, compressed, with smooth regu- 
larly convex margins. Dorsal margins slightly concave ; apical angle 
about 95 degrees. Right valve ornamented externally by 21-24 wide, 
moderately high, rounded ribs; on each side of major ribs is usually 
a faint auxiliary riblet ; interspaces between major ribs less than 
width of ribs ; anterior ear slightly longer than posterior, sculptured 
by about five low radial ridges and indistinct incremental lines ; pos- 
terior ear ornamented with about seven low, radial ridges and nearly 
invisible incremental lines. Left valve in general similar to right, but 
has higher, more strongly rounded, major ribs with narrow inter- 
spaces ; anterior ear with about seven radiating lines. Dimensions of 
rather small left valve of type : height, 37 mm. ; width, 33 mm. ; width 
of hinge line, 17 mm. 

Specimens of this species found in the Coalinga region have here- 
tofore been identified as Pecten deserti Conrad. On comparison of 
P. deserti from the type locality at Carrizo Mountain, San Diego 
County, with P. proteus, n. sp., several marked differences may be 
observed. In P. deserti the ribs are higher, flatter above, with more 
nearly vertical sides ; on the left valve the ribbing continues without 
interruption from eai's over the outer depressed dorsal margins, while 
in P. proteus, n. sp., the corresponding areas have no ribs. The ears 
of P. deserti are larger, more strongly curved, and have less depression 
where ears join dorsal margins of shell : also the dorsal margins show 
less marked concavity. These instances can be better recognized by 
seeing the comparative figures shown in this paper. 

Occurrence. — At localities 2991, 2975, with a large fauna charac- 
teristic of the Pecten coalingensis zone, upper Etchegoin. 



1917] Nomland: The Etchegoin Pliocene of Middle California 233 



MACOMA INQUINATA AFFINIS, n. var. 
Plate 9, figures 1, la, lb 
Type specimen, no. 11092, Univ. Calif. Coll. Invert. Palae. 

Shell large, equivalve, short, trapezoidal, with rather long liga- 
mental groove. Sides moderately convex, slightly excavated a little 
below anterior dorsal margin, giving a flange-like appearance, with 
depressed area on both valves extending from nmbones to posterior 
dorsal margin. Beaks low, adjacent, a little anterior to middle. 
Anterior margin evenly rounded, with increased convexity at anterior 
extremity ; posterior dorsal margin arcuate, with greater curvature 
behind ligamental groove ; posterior ventral margin concave where 
intersected by depression extending from beak, on most specimens base 
more strongly curved a little posterior to middle. Surface covered 
by numerous, unequal, concentric lines. Dimensions : height, 52 mm. ; 
length, 64 mm. 

This species may be distinguished from the typical Macoma inqui- 
nata (Deshayes) by its larger size, the flange immediately anterior to 
the beaks, depressed area extending from umbones to posterior ventral 
margin, rather long ligamental groove, and increased convexity near 
middle of base. 

Occurrence. — Locality 2965, Mya japonica zone, uppermost Etche- 
goin. 

SEMELE FAUSTA, n. sp. 
Plate 9, figures 3, 3a, 3b 
Type specimen no. 11102, Univ. Calif. Coll. Invert. Palae. 

Shell small, inequilateral, with moderately convex valves and low 
beaks. Posterior end much shorter than anterior ; anterior dorsal 
margin straight, with evenly rounded anterior end ; posterior dorsal 
margin slightly convex, with posterior end truncated inwards. Sur- 
face sculptured by numerous, about equidistant, low, concentric lines ; 
with a nearly obsolete fold extending from the beaks to the posterior 
end. Resilifer weak, narrow ; ligamental groove almost obsolete. 
Right valve with long, rather low laterals ; anterior cardinal indistinct, 
posterior cardinal low and slender ; left valve with feeble laterals and 
indistinct, thin cardinals. Dimensions : length, 35 mm. ; height, 30 mm. 

This form is of the same general type as Semele rubropieta Dall, 
from which it may be distinguished by its having a greater length in 
proportion to the width, the anterior portion being longer, the fold 



234 University of California Publications in Geology IT' 



more nearly obsolete, and by the long, straight, anterior dorsal margin. 
The hinge also differs in having the weak, narrow resilifer and long, 
narrow laterals, this being especially true of the anterior teeth. 

Occurrence. — At locality 2991, upper Etchegoin, on Zapato Creek, 
Fresno County ; at the type locality this species occurs with Thracia 
formosa, n. sp., Fissuridea unica, n. sp., Tegula (Chlorostoma) pulcella, 
n. sp., and the associated fauna. 

THKACIA FORMOSA, n. sp. 
Plate 9, figures 4, 4a 
Type specimen no. 11103, Univ. Calif. Coll. Invert. Palae. 

Shell small, inequilateral, thin, moderately compressed. Beaks 
low, about three-fifths length of shell from anterior end. Posterior 
dorsal margin slightly convex ; posterior end truncated. Junction of 
anterior dorsal and ventral margins marked by slight increase in con- 
vexity. Ventral margin evenly arcuate. Surface ornamented by dis- 
tinct, uniform, rounded, concentric ridges ; with a well developed, 
broad sulcation extending from the beak to the posterior extremity. 
Hinge weak ; right valve with small, rather thick tooth projecting at 
angle of nearly 45 degrees to plane of shell. Dimensions : height, 
27 mm. ; width, 19 mm. 

Occurrence. — At locality 2991, with a large fauna characteristic 
of the upper Etchegoin. 

FISSURIDEA UNICA, n. sp. 
Plate 11, figures 3, 3a, 3b 
Type specimen no. 11100, Univ. Calif. Coll. Invert. Palae. 

Shell subovate, conical, elevated, straight to slightly convex sides, 
with apex a little anterior. Ornamented by numerous prominent, 
rounded, rather thin, radiating ridges with narrow interspaces. In- 
cremental lines unequal, often more prominent than the radiating 
ridges. Apical orifice oblong, anterior to the apex, bounded inside by 
a posteriorly truncated callus. Dimensions of type, which is a rather 
small specimen : height, 14 mm. ; maximum diameter, 25 mm. ; mini- 
mum diameter, 19 mm. 

This species can readily be recognized by its height, ovate base, 
and radial ribbing with narrow interspaces. 

Occurrence. — In the upper Etchegoin, with a large fauna of the 
Pecten coalingensis zone at locality 2991. 



1917] Nomland: The Etchegoin Pliocene of Middle California 235 



TEGULA (CHLOEOSTOMA) PULCELLA, n. sp. 
Plate 12, figures 3, 3a 
Type specimen no. 11101, Univ. Calif. Coll. Invert. Palae. 

Shell conical, thin, with about six whorls ; suture distinct, ap- 
pressed. Sides of whorls fiat, giving an almost uniform slope from 
apex to base. Surface striated by faint, oblique, incremental lines 
and numerous low, rounded, axial riblets; on the sides of the whorls 
near the base are about three fine spiral threads. Base of body- whorl 
flattish, with sharp angle at periphery ; ornamented by incremental 
lines and two or three nearly obsolete spirals around umbilical area. 
Aperture subquadrate, with thin outer lip ; inner lip with two small 
tubercles, of which the lower is almost invisible. Umbilicus open ; 
outer edge of umbilical area limited by a distinct, sharp ridge. Height, 
23 mm. ; diameter of slightly deformed type, 26 mm. 

This species is easily recognized by its flat sides, conical form, and 
low axial ornamentation. 

Occurrence. — At locality 2991, with a large fauna of the Pecten 
coalingensis zone, upper Etchegoin. 

CHEYSODOMUS PACKAEDI, n. sp. 

Plate 12, figures 4, 4a, ib 
Type specimen no. 11096, Univ. Calif. Coll. Invert. Palae. 

Shell thick, has about four or five rapidly increasing whorls, with 
distinct, appressed suture. Whorls slightly convex, tabulate, almost 
channeled above. Surface of whorls ornamented by coarse, square, 
spiral ribs, between which are fine thread-like intercalates and narrow 
interspaces ; on body-whorl and continuing nearly to lower end of 
canal there are about nine and on the whorls of spire three of these 
major spirals. Crossing the whorls, and especially evident on spire, 
are numerous longitudinal ribs ; on body-whorl of some specimens these 
ribs become nearly obsolete ; where spirals cross the axial ribs a retic- 
ulate appearance is produced. Aperture rectangular, forming a short, 
wide canal; with thin, sharp, outer lip; inner lip incrusted, smooth. 
Dimensions of type : diameter, 17 mm. ; height unknown. 

Occurrence. — At localities 2958, 2985, middle Etchegoin. At the 
type locality near middle of western boundary of NW % of NW 14 
sec. 8, T. 23 S, R. 17 E, M. D. B. & M., this species occurs with the 
following species: Area trilineata Conrad, Calliostoma. cf. kerri Ar- 



236 



University of California Publications in Geology [Vol. 10 



nold, Calyptraea filosa (Gabb), Dendraster, sp., Macoma, cf. inquinala 
(Desbayes), Nassa calif orniana (Conrad), Ostrea atwoodi Gabb, 
PapJria staminca (Carpenter), Thais kettlemansis Arnold, Trophon, 
sp., Turritella, cf. nova Nomland. 

MUREX (OCINEBRA) CONCINNA, n. sp. 
Plate 12, figures 6, 6a 
Type specimen no. 11093, Univ. Calif. Coll. Invert. Palae. 

Shell small, subfusiform, with rather low spire. Whorls four or 
more, increasing rapidly in size. Body-whorl with distinct angles at 
shoulder and base, giving the sides a flattened appearance. Each 
whorl with about nine wide, prominent, axial ribs ; on body-whorl these 
extend from suture down to about middle of canal. The spiral orna- 
mentation on the body-whorl consists of about eight and on the spire 
two, high, rounded cords which become fainter on canal ; between these, 
especially on upper part, are fine thread-like intercalaries ; where the 
spirals intersect the axial ribs a decidedly nodose appearance is pro- 
duced. Aperture oblong-elliptical ; outer lip thickened, terminating 
in a long, narrow, recurved canal ; inner lip slightly incrusted ; colu- 
mella faintly marked by spiral sculpture. Dimensions : height, 25 mm. ; 
maximum diameter, about 13 mm. 

Occurrence. — At localities 2643, 2985, middle Etchegoin. 

MUREX (OCINEBRA) TETHYS, n. sp. 
Plate 12, figures 2, 2a, 2b 
Type specimen no. 11099, Univ. Calif. Coll. Invert. Palae. 

Shell small, heavy ; whorls four or five ; suture distinct, slightly 
channeled ; apex acute ; body-whorl large and ventricose. Whorls 
sculptured by prominent, coarse spiral cords and low, often almost 
invisible, intercalaries ; the body-whorl has about seven and the spire 
two of the major cords ; these are crossed by eight high, angular, longi- 
tudinal ribs which disappear on lower part of body- whorl; where these 
cross the spirals the shell becomes slightly nodose, this being especially 
evident on upper part of whorls, where a rather sharp shoulder is 
produced. Aperture wide, elliptical, with thick outer lip ; inner lip 
apparently smooth, incrusted ; canal short, slightly curved. Dimen- 
sions of type : height, 21 mm. ; diameter, 15 mm. 

Apparently this form most closely resembles Ocinebra lurida, var. 
ccrritensis Arnold, from which it may be distinguished by its higher 



1917] Nomland: The Etchegoin Pliocene of Middle California 237 



and more acute spire, the presence of small spiral intercalates, and 
the sharper angle at shoulder of whorls. 

Occurrence.— At localities 2986, 2985, 2988, 2643; middle Etche- 
goin. 

TEOPHON BELCHEEI AVITUM, n. var. 
Plate 11, figure 5 
Type specimen no. 11094, Univ. Calif. Coll. Invert. Palae. 

Shell large, heavy, with five or more whorls ; spire moderately 
elevated ; suture appressed. Whorls angulate at shoulder, with promi- 
nent angle at lower part of body-whorl ; immediately below this is a 
deep groove which varies considerably in size in different specimens 
and in front of which the lower part of body-whorl protrudes. Whorls 
and canal ornamented by about eleven raised axial folds or varices 
which at the shoulder become sharp spines, also at lower angle of 
body-whorl where intersected by varices the shell usually becomes 
nodose. Outer lip thin, canal slightly recurved. Height of type, 
66 mm. ; diameter of body -whorl, 60 mm. 

This species differs from Trophon belcheri Hinds by shorter and 
stouter nodes at shoulder, rather prominent nodes near base of body- 
whorl, shorter columella, and lower spire than most specimens of 
T. belcheri. From T. magister Nomland it differs in having a larger 
number of varices, in being more spinose at shoulder, and by more 
evident development of nodes on lower part of body-whorl. 

An interesting problem in evolution could probably be solved by 
a study of the large Trophons having the characteristic groove imme- 
diately below the body-whorl. In the lower Miocene this type first 
appears as T. gabbianum Anderson ; in the upper Miocene it takes the 
form of T. carisaensis Anderson ; in the Pliocene we find T. magister 
Nomland, while the Recent form is T. belcheri Hinds. 

Occurrence. — -At locality 2988, middle Etchegoin. 

CANCELLAEIA CEASSA, n. sp. 
Plate 12, figures 7, 7a 
Type specimen no. 11098, Univ. Calif. Coll. Invert. Palae. 
Shell slender, solid, with about five whorls; suture distinct, im- 
pressed. Whorls sharply angulated a little less than one-third of the 
distance below suture, somewhat tabulate above ; near the base of the 
body-whorl is another distinct angle, giving the periphery of whorls 



238 



University of California Publications in Geology [Vol. 10 



a flattened appearance. Axially sculptured by eleven prominent ribs 
which become less marked on the tabulate portion above, on the body- 
whorl these extend only to lower peripheral angle. Spiral sculpture 
on the body-whorl consists of seven and on the spire five strongly 
elevated cords. Outer lip of type defective. Aperture narrow, with 
long twisted canal. Inner lip slightly incrusted, pillar long and 
slender, with two thin, sharp plaits on the lower part. Height, about 
41 mm. ; diameter, 20 mm. 

Occurrence. — At locality 2533, near middle of southern boundary 
of NW y 4 of NE 14, sec. 29, T. 21 S, R. 14 E, M. D. B. & M., on north 
bank of Waltham Creek. At the type locality this form occurs with 
the following characteristic Etchegoin species : Macoma vanvlecki 
Arnold. Pecten terminus Arnold, Pecten oweni Arnold, Phacoicles 
annulatus (Reeve), Bathytoma tryoniana (Gabb), Ficus nodiferous 
Gabb, Tunis coalingensis (Arnold), Thais kettlemanensis Arnold, 
Turritella nova Nomland. 

CANCELLAEIA FEENANDOENSIS TB1BULIS, n. var. 

Plate 12, figures 1, la 
Type specimen 110. 11095, Univ. Calif. Coll. Invert. Palae. 

Shell broadly fusiform, spire high, with about four whorls ; body- 
whorl large ; suture distinct, almost channeled. Wborls with sharp 
angle immediately below suture, giving a tabulate appearance to the 
upper part ; sculptured with about sixteen prominent axial ribs, 
which on the body-whorl become less distinct above the shoulder 
and are almost obsolete on the canal. Spiral ornamentation on the 
body-whorl consisting of twenty-two, and on the whorls of the spire 
about nine, nearly equal cords with narrow interspaces, which on 
crossing the axial ribs form nodes. Aperture ovate, forming a short, 
slightly twisted canal. Pillar nearly straight, covered by a thin 
coat of callus ; with two broad, low plaits with wide interspaces. 
Dimensions: height, 34 mm.; diameter, 19 mm. 

This variety has fewer axial ribs, shoulder is higher up on the 
whorls, upper surface of whorls more distinctly tabulate, and whorls 
enlarge more rapidly than the typical form. 

Occurrence. — At locality 2964, on low hills near divide between 
Big Tar Creek and Garza Creek, near center of NE y± of NW 14, sec. 
7, T. 23 S, R, 17 E, M. D. B. & M., middle Etchegoin Pliocene. At the 
type locality this species occurs with a fauna including the following 



1917] Nomland: The Etchegoin Pliocene of Middle California 239 



species: Area trilineata Conrad, Chrysodomus portolaensis (Arnold), 
Dendraster gibbsii (Remond), Olivella biplicata Sowerby, Paphia 
staminea (Carpenter), Peeten, ef. healcyi Arnold, Peeten terminus 
Arnold. 

PECTEN ETCHEGOINI Anderson 
Plate 7, figures 1 to 5 
Peeten etchegoini Anderson, Proc. Calif. Acad. Sci., vol. 2, p. 198, pi. 18, 
figs. 92-93, 1905. 

Peeten wattsi, var. morani Arnold, IT. S. Geol. Surv. Prof. Paper 47, pp. 

121-122, pi. 10, figs. 3-6, 1906. 
Peeten wattsi Arnold, var. etchegoini Anderson, U. S. Geol. Surv. Bull. 

396, p. 77, 1909. 

On obtaining a large number of specimens from the type localities 
of Pecten etchegoini Anderson, P. nutteri Arnold, and P. wattsi 
Arnold a difficulty was at once experienced in attempting a separation 
of these forms. By closer study it was found that the prominence of 
the ribs of P. etchegoini varies greatly. Also the nodose constrictions 
characteristic of P. wattsi vary much in prominence. It became evi- 
dent that series could be found for both valves showing a gradation of 
P. nutteri and P. wattsi into P. etchegoini. Figures are given in the 
present paper showing gradational series. P. nutteri Arnold and 
P. wattsi Arnold are therefore here used as variations of P. etchegoini 
Anderson. 

SEBPULA (?), sp. 

Figure 2 , 

On the south bank of Garza Creek, in the Coalinga district, is 
exposed a bed composed almost exclusively of tubules believed to 
represent the genus Serpula. The tubules are about 1.5 mm. in 
diameter and are closely packed together, forming an almost solid 
mass. 




Pig. 2. Serpida {?), sp. X 2. 



240 



University of California Publications in Geology [Vol. 10 



CANCELLAEIA EAPA, n. sp. 
Plate 11, figures 1, la 
Type specimen no. 11097, Univ. Calif. Coll. Invert. Palae. 

Shell thick, ventrieose, with about five or six rapidly enlarging, 
regularly convex whorls, apex rather blunt. Suture marked by a dis- 
tinct line, slightly appressed. Sculpture consisting of spiral ridges 
crossed by low axial riblets. Spiral sculpture on the body-whorl 
marked by about eighteen nearly square major ribs ; between most of 
these are less prominent intercalaries with interspaces narrower than 
the latter. Axial riblets not regularly spaced, nearly obsolete, be- 
coming entirely so on lower half of body-whorl. Aperture semilunar, 
outer lip broken, forming a short canal at base. Pillar thinly incrusted 
and with four plaits, of which the middle and lowest are less prominent. 
Height of type, 53 mm. ; diameter, 29 mm. 

Occurrence. — The type in the University of California collections, 
obtained by L. D. O'Neal, is labeled as having come from the 
Pliocene ( ?) near Coalinga, Fresno County, California. 



EXPLANATION OF PLATE 6 
All figures approximately natural size 

Fig. 1. Pecten deserti Conrad. Eight valve; from the type locality at Car- 
rizo Creek, San Diego County; Carrizo formation, Pliocene. 

Fig. la. Pecten deserti Conrad. Left valve; from the type locality. 

Fig. lb. Pecten deserti Conrad. Profile view from the rear of the same 
specimen as figure la; showing on the left valve ribbing continuing from body 
over ears without interruption. 

Fig. 2. Pecten proteus, n. sp. Left valve of type from locality 2991; Univ. 
Calif. 11089; Pecten eoalingensis zone, upper Etchegoin. 

Fig. 2a. Pecten proteus, n. sp. Eight valve; from locality 2991. 

Fig. 2b. Pecten proteus, n. sp. Eight valve; from locality 2991. 

Fig. 2c. Pecten proteus, n. sp. Profile view from rear of same specimen as 
figure 2; showing unribbed area immediately above ear. 

Fig. 3. Pecten egregius, n. sp. Left valve; from locality 2975; Pecten eo- 
alingensis zone. 

Fig. 3fl. Pecten egregius, n. sp. Eight valve of type; from locality 2991, 
no. 11090, Pecten eoalingensis zone, upper Etchegoin. 

Fig. 3b. Pecten egregius, n. sp. Profile view from rear of same specimen 
as figure 3a. 

Fig. 4. Pecten terminus Arnold. Eight valve; from locality 2523. This 
species was described as a variety of Pecten estrellanus Conrad by Arnold. 



[242] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL. 



[NOMLAND] VOL 10, PL, 6 




EXPLANATION OF PLATE 7 



All figures natural size, left valve. Figures 1 to 4 from locality 2975. 
Figures showing gradation of Pecten wattsi Arnold and Pecten nutteri Arnold 
into Pecten etchegoini Anderson. 

Fig. 1. Pecten etchegoini Anderson. From the type locality of the species, 
Zapato Creek, Fresno County. 

Fig. la. Pecten etchegoini Anderson. 

Fig. lb. Pecten etchegoini Anderson, or P. etchegoini, var. wattsi Arnold. 
Fig. lc. Pecten etchegoini wattsi Arnold. From the type locality of the 
variety, Zapato Creek, Fresno County. 

Fig. 2. Pecten etchegoini wattsi Arnold. 

Fig. 8. Pecten etchegoini wattsi Arnold, or var. nutteri Arnold. 
Fig. 4. Pecten etchegoini nutteri Arnold. From the locality from which 
Arnold 's material was obtained, Zapato Creek, Fresno County. 
Fig. 5. Pecten etchegoini nutteri Arnold. From locality 2982. 



[244] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL 



[NOMLAND] VOL. 10, PL. 7 




EXPLANATION OF PLATE 8 



All figures approximately natural size 

Fig. 1. Cryptomya quadrata Arnold. Eight valve; from locality 3005, Priest 
Valley, Monterey County. 

Fig. la. Cryptomya quadrata Arnold. Left valve; from same locality as 
figure 1. 

Fig. 2. Peeten etchegoini Anderson. Eight valve; from locality 3004, Priest 
Valley, Monterey County. 

Fig. 2a. Pecten etchegoini Anderson, or P. etchegoini nutteri Arnold. Eight 
valve of an intermediate form; from locality 3004. 

Fig. 2b. Pecten etchegoini nutteri Arnold. Eight valve; from locality 3004. 

Fig. 3. Macoma vanvlecJci Arnold. Eight valve; from locality 2526, Jaca- 
litos Creek, Fresno County. 

Fig. 3a. Macoma vanvlecki Arnold. Left valve; from locality 2526. 



[246] 



UNIV, CALIF. PUBL. BULL. DEPT. GEOL. [NOMLAND] VOL. 10, PL 




EXPLANATION OF PLATE 9 
All figures approximately natural size 

Fig. 1. Hacoma inguinata affmis, n. var. Left valve; no. 11092; from 
locality 2965, Garza Creek, Kings County, uppermost Etehegoin. 

Fig. la. Macoma inquinata affinis, n. var. Eight valve of same specimen 
as figure 1. 

Fig. lb. Macoma inquinata affinis, n. var. Profile view of valves shown in 
figures 1 anil ]n. 

Fig. 2. Anodonta nitida, n. sp. Left valve; a fresh-water species from 
locality 2999, no. 11(191, Kettleman Hills, Kings County. 

Fig. 3. Semele fausta, n. sp. Right valve; from locality 2991, Zapato Creek, 
Fresno County; no. 11102; Pecten coalingensis zone, upper Etehegoin. 

Fig. 3a. Semele fausta, n. sp. Hinge of left valve; from locality 2991. 

Fig. '.'>b. Semele fausta, n. sp. Hinge view of same specimen as figure 3. 

Fig. 4. Thracia formosa, n. sp. Left valve; from locality 2991, Zapato 
('reek, Fresno County; no. 11103; Pecten coalingensis zone, upper Etehegoin. 

Fig. 4k. Thracia formosa, n. sp. View of hinge of same specimen as 
figure 4. 



[248] 



UNIV. CALIF. PUBL BULL. DEPT. GEOL. 



[NOMLAND] VOL. 10, PL. 9 




EXPLANATION OF PLATE 10 
Figures approximately of natural size 

Fig. 1. Dosinia jacalitosana Arnold. Exterior of right valve; from locality 
3012, Priest Valley, Monterey County; lower Etehegoin. 

Fig. la. Dosinia jacalitosana Arnold. View of hinge of right valve; from 
locality 3012. 



[250] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL. 



[NOMLAND] VOL. 10, PL. 10 




EXPLANATION OF PLATE 11 



All figures approximately natural size 

Fig. 1. Cancellaria rapa, n. sp. Mouth view; no. 11097; Etchegoin Pliocene. 

Fig. la. Cancellaria rapa, n. sp. Opposite view of same specimen as figure 1. 

Fig. 2. Epitotiiurn varicostata Stearns. Mouth view; from locality 2975, 
Zapato Creek, Fresno County; Pecten coalingensis zone, upper Etchegoin. 

Fig. Fissuridea unica, n. sp. Top view of type; no. 11100; from locality 
2991, Zapato Creek, Fresno County; Pecten coalingensis zone, upper Etchegoin. 

Fig. '.'>a. Fissuridea unica, n. sp. Side view of same specimen as figure 3. 

Fig. 3ft. Fissuridea unica, n. sp. Side view of a specimen of medium size; 
from locality 2991. 

Fig. 4. Purpura turris Nomland. Mouth view; from locality 2680; occurs 
in both lower and upper Etchegoin. 

Fig. 4a. Purpura turrix Nomland. Opposite view of same specimen as 
figure 4. 

Fig. 5. Trophon belcheri avitum, n. var. View of back; no. 11094; from 
locality 2988, Zapato Creek, Fresno County; middle Etchegoin. 



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UNIV, CALIF. PUBL. BULL. DEPT. GEOL 



[NOMLAND] VOL. 10, PL. I 




EXPLANATION OF PLATE 12 
All figures approximately natural size 

Fig. 1. Cancellaria femandoensis tributes, n. var. Mouth view; bo. 11095; 
locality 2964, Garza Creek, Kings County; Turritella nova zone. 

Fig. la. Cancellaria femandoensis tributes, n. var. Same specimen as figure 
1 viewed from opposite side. 

Fig. 2. Murex tethys, n. sp. Back view of type; no. 11099; from locality 
2986, Zapato Creek, Fresno County, middle Etchegoin. 

Fig. 2a. Murex tethys, n. sp. View of back of a small specimen; from 
locality 2643. 

Fig. 2b. Murex tethys, n. sp. Mouth view of same specimen as figure 2. 

Fig. .'!. Tegula (Chlorostoma) pulcella, n. sp. From locality 2991, Zapato 
Creek, Fresno County; no. 11101; Pecten coalingensis zone, upper Etchegoin. 

Fig. 3a. Tegula (Chlorostoma) pulcella, n. sp. Same specimen as figure 3; 
view of distorted and broken base. 

Fig. 4. Chrysodomus paclcardi, n. sp. View of back of type; no. 11096; from 
locality 2958, Big Tar Creek, Kings County; middle Etchegoin. 

Fig. 4a. Chrysodomus paclcardi, n. sp. Mouth view of distorted specimen 
from locality 2985. 

Fig. 4i>. Chrysodomus paekardi, n. sp. View of back of specimen from 
locality 2958. 

Fig. 5. Turritella vanvlecM Arnold. From locality 2377, the type locality 
of the species. 

Fig. 6. Murex cone i una, n. sp. Mouth view; no. 11093; from locality 2643, 
lower Etchegoin. 

Fig. 6a. Murex coneinna. n. sp. View of back of same specimen as figure 6. 
Fig. 7. Cancellaria crassa, n. sp. Mouth view; no. 11098; from locality 2533, 
Waltham Creek, Fresno County; Turritella nova zone, middle Etchegoin. 

Fig. 7a. Cancellaria crassa, n. sp. Back view of same specimen as figure 7. 



[254] 



UN!V. CALIF. PUBL. BULL. DEPT. GEOL. [NOMLAND] VOL. 10, PL. 12 




UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

), No. 15, pp. 255-266, plate 13 Issued April 14, 1917 



AGE OF STRATA REFERRED TO THE ELLENS- 
BURG FORMATION IN THE WHITE BLUFFS 
OF THE COLUMBIA RIVER 



BY 



JOHN C. MERRIAM and JOHN P. BUWALDA 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN 'JF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 15, pp. 255-266, plate 13 Issued April 14, 1917 



AGE OF STRATA REFERRED TO THE ELLENS- 
BURG FORMATION^ TI±E WHITE BLUFFS 
OF THE COLUMBIA RIVER 

BY . ' , 

JOHN C. MERRIAM and JOHN P. BUWALDA 



CONTENTS 

PAGE 

Introduction . 255 

Previous knowledge 256 

Faunas 257 

Geology 260 

Stratigraphic section 260 

Physiography and structure 261 

Mode of deposition 263 

Area 263 

Relation to the Ellensburg formation 264 



INTRODUCTION 

As a part of a programme of correlation studies on the Tertiary in 
the northern part of the Great Basin, the writers visited important 
localities of the Ellensburg formation of south-central Washington 
in June, 1916, in the hope of adding to the scanty representation of 
vertebrate remains known from these beds. A small collection was 
secured in the type area of the Ellensburg formation near North 
Yakima. A somewhat larger quantity of fragmentary material was 
collected in the great section of sediments appearing in the White 
Bluffs of the Columbia River in the vicinity of Hanford and Ringold, 
generally recognized as one of the largest of the typical Ellensburg 
exposures. 

In the typical Ellensburg area near North Yakima remains of 
an equid or horse type were found representing the genus Hipparion, 



256 University of California Publications in Geology [Vol. 10 



a group especially well represented in the earlier Pleistocene of 
western North America. From the White Bluffs localities the only 
determinable specimens representing the horse family belong to an 
advanced or specialized species of the genus Equus. In the widely 
known North American occurrences of Equus there is as yet no 
reported discovery of a species of such an advanced type in beds 
earlier than Pleistocene. 

It is quite certain that the evolution stages of the horses rep- 
resented by the Ellensburg and White Bluffs specimens belong to 
widely different periods, of which the White Bluffs stage is the 
later. The Ellensburg formation is evidently Miocene to early Plio- 
cene in age ; the White Bluffs exposures represent a distinct and 
considerably later stage in the history of sedimentation in the eastern 
Washington region. 

It is the purpose of the following paper to give a brief statement 
concerning the physiographic and geologic features and the fauna 
of the White Bluffs exposures, which are here described as the 
Ringold formation. 

Owing to brevity of the time spent in the Ringold area by the 
writers, data concerning structure of the formation, extent of the 
area occupied, and stratigraphic relations to the Ellensburg formation 
must be considered incomplete. 

PREVIOUS KNOWLEDGE 

The White Bluffs section was considered by I. C. Russell 1 "the 
most typical section of the John Day beds to be seen in Washington." 
As the name John Day was used by Russell with reference to the 
formation now known as the Ellensburg, it is to be presumed that 
he considered the White Bluffs approximately contemporaneous with 
the Ellensburg. The exposures were stated by Russell to range up to 
500 feet in height, and to be composed of approximately horizontal 
or only slightly tilted strata. The beds were reported to consist of 
fine sands, clays, and strata of volcanic ash. A section taken at the 
southern end of the cliffs measured 496 feet in thickness. 

Russell - reported that fossil bones of large animals had been 
found in the White Bluffs beds, but that their significance was not 
known. The exposures were considered favorable ground for collect- 
ing vertebrate remains. Reference was made to deposits presumed 

1 U. S. Geol. Surv. Bui. no. 108, p. 97, 1893. 

2 Ibid., p. 98. 



1917] Mcrriam-Buwalda: White Bluffs of the Columbia 257 

to be Pleistocene in the region occupied by the White Bluffs sedi- 
ments, and the possibility noted of confusing Pleistocene and White 
Bluffs beds. Russell mentioned a locality at the southern end of 
the White Bluffs exposures, about fifteen miles above Pasco, where 
a number of large fossil bones, assumed to have been derived from 
the White Bluffs beds, were found in a river terrace banked against 
a cliff formed of horizontal White Bluffs strata. He stated that no 
molluscan shells were found in the sediments, and suggested the 
possibility that immense quantities of volcanic dust falling into the 
water may have made it unfavorable for animal life. 

In 1903 George Otis Smith 3 referred to the White Bluffs exposures 
described by Russell, and called attention to evidence indicating that 
while in the Yakima region the Ellensburg formation is of fluviatile 
origin, farther east along the Columbia the formation is of lacustrine 
character. 

Calkins 4 discussed the White Bluffs in 1905, and gave from the 
upper end of the cliffs a section 225 feet in thickness, consisting 
of sands and clays with some ashy material. Other writers were 
followed in correlating the White Bluffs exposures with the Ellens- 
burg, but Calkins noted that "the general character of this section 
offers some points of contrast with the typical section measured in the 
Ellensburg Quadrangle." The materials included in the White Bluffs 
exposures were shown to be fine and less commonly cross-bedded than 
in the typical Ellensburg, and tuffaceous material was stated to be 
less abundant. The suggestion was made that a part of the White 
Bluffs beds may be of lacustrine origin, but that certain of the sandy 
layers were probably laid down in rivers. Calkins found no fossils 
in the White Bluffs exposures, but noted the reported occurrence of 
shells and bones in the bluffs near Pasco. 

FAUNAS 

In examining the White Bluffs in June, 1916, the authors collected 
mammalian material from exposures about midway between the base 
and the summit of the bluffs on the east side of the Columbia three to 
four miles below Hanford (loc. 3031). Later in the summer a small 
collection was secured one or two miles north of Ringold School (loc. 
2757) a few miles south of the first locality. 

a U. S. Geol. Surv. Professional Paper no. 19, p. .18, 1903. 
4 Calkins, F. C, U. S. Geol. Surv. Water Supply and Irrigation Paper no. 118, 
p. 35, 1905. 



258 University of California Publications in Geology [Vol. 10 



The collection from the locality near Hanford (loc. 3031) in- 
cludes the following forms : 

Megalonyx, small species, probably new. 

Equus or Pliohippus, ealeaneum 

Oamelid, small, near Pliauehenia 

Camelid, possibly larger than first mentioned form 

Cervid, antler fragments 

Leporid, new genus 

Fish vertebrae and other elements of skeleton 
Testudo, fragments 

With the exception of the ground-sloth remains the material from 
locality near Hanford (loc. 3031) is not well preserved, and this 
form furnishes the only type diagnostic of any recognized faunal 
stage. 

The Megalonyx specimen consists of a well-preserved maxillary 
with all four cheek-teeth in perfect condition. The species resembles 
the Pleistocene M. whcatlyi in size, but is probably new. 

A single specimen representing the horse group consists of a 
considerably worn ealeaneum or heel bone somewhat smaller than the 
average of ealcanea of the Pleistocene horses, and exceeding little if 
any the average of Pliohippus from the West Coast Pliocene. It is 
considerably larger than the specimens commonly found in the West 
Coast Miocene. 

Of the camel remains none of the fragments can be generically 
determined with certainty. A portion of a tooth and an incomplete 
proximal toe bone seem to represent a type not more advanced than 
those of the later Tertiary. They appear smaller and less specialized 
than the known forms of the West Coast Pleistocene. 

Deer are represented by fragments of antlers, some of which show 
the burr well preserved. The deer of the Pleistocene and later Ter- 
tiary are not as yet well enough known to furnish a good basis for 
comparison of the fragments represented in the White Bluffs col- 
lection. 

A single upper cheek-tooth of a rabbit-like form obtained in the 
White Bluffs beds is considered by Dr. Lee R. Dice to resemble in 
its tooth-pattern a new genus known from the middle Miocene and 
early Pliocene of northern Nevada. In this specimen the enamel 
folds on the re-entrant angle are comparatively coarse, in contrast to 
the finer folds seen in the teeth of the later rabbits. 

The fish and tortoise remains have not shown characters furnishing 
definite evidence concerning geologic position. 



1917] Merriam-Buwalda: White Bluffs of the Columbia 



259 



The material obtained one to two miles north of Ringold School 
(loc. 2757) includes upper and lower cheek-teeth and fragments of 
the skeleton of a horse in which all the characters noted are those 
of an advanced member of the genus E quits. 

In the upper cheek-teeth the protocone is long anteroposteriorly, the anterior 
lobe projects far in advance of the isthmus connecting it with the protoeonid, 
and the inner wall is markedly concave. The fossetts are narrow, and the bor- 
ders show fairly complicated folds. In the lower cheek-teeth the inner faces of 
the protoeonid and hypoconid are flat. The metaconid-metastylid column is long 
anteroposteriorly and broadly grooved internally. The valleys anterior and 
posterior to the metaconid-metastylid column are narrow transversely, as in 
Equus. The parastylid is short. A single splint bone representing digit four 
of the posterior foot is very short, and though the tip is absent the splint narrows 
so rapidly below that phalangeal elements must have been absent. 

It is difficult to make certain of the specific identity of isolated 
Equus teeth, but the specimens from near Ringold School are at least 
as advanced as those of Equus occidentalis from the Pleistocene of 
Rancho La Brea, and may be even more specialized. 

The assemblage of forms from the White Bluffs near Hanford 
taken as a whole seems more advanced than any fauna know hereto- 
fore in the Miocene of the Pacific Coast and Great Basin provinces. 
Megalonychid sloths are reported from the Pliocene, but are im- 
perfectly known and of doubtful systematic position. Deer such as 
are represented in the collection are not known in Miocene beds of 
the Great Basin province. The earliest reported occurrence of typical 
deer in the region west of the Wasatch is in the latest Etchegoin 
Pliocene of the Coalinga region. The fragmentary camel remains 
might represent late Tertiary. They seem of earlier type than any 
known to the writers from the "West- American Pleistocene. The frag- 
mentary equid specimen might be from a late Tertiary or from a 
Pleistocene form. 

The collection from near Ringold School taken by itself would be 
considered to represent Pleistocene. 

The question of relative age of the material from the two White 
Bluffs localities naturally presents itself. There is some suggestion 
of difference in preservation between the two collections. The fossil 
specimens from near Ringold School show somewhat less evidence of 
corrosion and decay. In order to determine whether one collection 
might have been derived from the strata in the White Bluffs and the 
other from terrace deposits laid down against them, as reported by 
Russell 5 in the case of certain other deposits containing fossils at the 



260 University of California Publications in Geology [Vol. 10 

southern end of the bluffs, both localities were carefully investigated. 
It was found that at both stations the bones were derived from layers 
of sand and gravel in the steep faces of the White Bluffs, a little 
below the middle of the exposed section, and that the strata yielding 
the fossils are part of the White Bluffs section and not terrace de- 
posits. The locality one to two miles north of Ringold School is shown 
near the right-hand end of figure 1 in plate 13. 

There is every reason for considering that the collections secured 
near Hanford (loc. 3031) and near Ringold School (loc. 2757) rep- 
resent approximately the same horizon in the White Bluffs sediments. 
The best preserved specimens from both localities seem to furnish 
definite evidence of very late Cenozoic age. The ground-sloth jaw 
from the Hanford locality and the Equus teeth from the Ringold 
School locality both represent types generally considered characteristic 
of the Pleistocene. 

As the separation between the Pliocene and Pleistocene is not yet 
clearly determined on a faunal basis in the Great Basin region, one 
might admit for the present the possibility of including in the latest 
Pliocene the faunal stage represented in the White Bluffs exposures. 
Not even the latest faunas referred to the Pliocene up to the present 
time includes horses of a stage as advanced as that of the Ringold 
School fauna, and the evidence on the whole favors Pleistocene rather 
than the latest Pliocene. 

GEOLOGY 

Stratigraphic Section. — From a point twelve miles above the town 
of Pasco, in south-central Washington, bluffs several hundred feet in 
height extend about thirty miles northwestward along the eastern 
bank of the Columbia River. Because of their light color these 
magnificent exposures have commonly been known as the White 
Bluffs. 

The strata in the White Bluffs clearly represent a formation 
distinct from the Ellensburg, as is indicated by the difference in age 
expressed in their faunas, and by the physical evidence. The writers 
propose the name Ringold formation for these beds, from Ringold 
Post Office, situated at the base of the bluffs. The known thickness 
of these strata exposed by the downcutting of the Columbia River is 
approximately 500 feet; as the river has not reached the base of the 
section the total thickness is not known. The Ringold formation 

5 Russell, L C, U. S. Geol. Surv. Bui. no. 108, p. 99, 1893. 



1917] Merriam-Buwalda: White Bluffs of the Columbia 261 



consists, as noted by earlier writers, chiefly of light-colored muddy 
sandstones and sandy clays, and in minor part of fine gravels, volcanic 
ash and calcareous strata. 

The following is an estimated section of the Ringold formation 
in the "White Bluffs three to four miles below Hanf ord : 

Feet 



7. Loose yellowish clayey sand (summit of section) 85 

6. Gray limestone, often brecciated, irregular in thickness, forming a resist- 
ant layer 3 

5. Cream-colored clayey sandstone, lacking resistance to weathering 75 

4. Brownish-yellow clayey sandstone, distinctly but thickly bedded, more re- 
sistant, standing out as bluffs 75 

3. Yellow sandy clay, unindurated, poorly stratified 25 

2. Cream-colored clay, thinly bedded, including occasional thin layers of 

sandy material, giving quite prominent outcrops 25 

1. Nearly white clayey sandstone, in places pure sand, witli occasional thin 
gravel layers of polished quartz pebbles. Fossils occurring near top 
of this member, which extends from the Columbia River up to an ele- 
vation of about 175 feet above the river 175 

Approximate thickness of section exposed above Columbia River .... 503 



Viewed from a distance individual beds may appear quite per- 
sistent in the face of the bluffs, but the bulk of the material is not 
thoroughly classified as to size, and therefore not sharply stratified. 
The coarser materials are waterworn. Occasionally beds of coarse 
angular materials, chiefly basaltic in character, are found at the top 
of the bluffs, but these are evidently later deposits laid down in chan- 
nels cut in the Ringold by water courses heading in the country to the 
east and north. The strata of the Ringold lack induration and are 
notably softer than most exposures of the Ellensburg. "While they 
exhibit steep slopes, especially where the Columbia has recently cut 
into the base of the bluffs, exposures tend to assume rounded outlines 
and a subdued topography, even under the prevalent conditions of 
semi-aridity. 

Physiography and Structure. — Direct observations on the struc- 
ture of the Ringold were limited to the "White Bluffs exposures, but 
certain inferences as to the attitude of these beds in other parts of 
the area seem possible from physiographic considerations. So far as 
could be judged, the strata in the "White Bluffs lie parallel to the 
water surface of the Columbia River. All recognized cases of appar- 
ent deformation seem to be due to landslide. 

The WTiite Bluffs follow the river closely from a point ten or 
twelve miles north of Pasco to the northwestward for about thirty 



262 University of California Publications in Geology [Vol. 10 

miles. The bluffs end at a point across the river and a short distance 
below the town of White Bluffs. Where the beds are not locally re- 
duced by erosion, the crest line of the bluffs is remarkably even (pi. 
13, fig. 2). Without having determined its elevation above the river 
at many points, the crest appears to maintain its height of about 
five hundred feet above the stream throughout the whole thirty miles. 

Between the northwestern end of the White Bluffs and Priest 
Rapids, a distance of fifteen to eighteen miles upstream, no high 
bluffs occur, but low light-colored exposures appear some distance 
from the river. The dissected character of this area indicates that it 
has suffered marked degradation in contrast to the relatively undis- 
sected areas lying to the east of the Columbia in the Ringold region. 
The more marked dissection has probably resulted from the greater 
drainage derived from the Saddle Mountains to the north. 

The White Bluffs, extending along the east side of the Columbia 
River, have no counterpart in similar features on the opposite side 
of the stream. To the west of Hanford is an area with a rolling 
topography, on which occur occasional outcrops of soft beds similar 
to those in the White Bluffs. This area extends westward to the base 
of the Yakima Range and has a maximum width of perhaps sixteen 
miles. Practically all of it lies at less elevation above the Columbia 
than the top of the White Bluffs. It is believed that the Ringold once 
extended over this region of low hills between Hanford and the base 
of the Yakima Range, and that it was largely cut away by the Colum- 
bia before it had shifted eastward to its present position, and while 
its channel lay at a higher level. It has been this gradual shifting 
eastward, continued to the present time, which has produced the 
White Bluffs on the east side of the Columbia, in contrast to the de- 
graded character of the area on the west side. The cause of the 
shifting cannot be stated with certainty, but it is probably due in 
part to deflection of the stream by the north side of the Yakima 
Range. 

The surface extending several miles to the eastward from the 
summit of the White Bluffs is remarkably even, excepting where in- 
terrupted by occasional drainage courses which have cut below its 
level. The marked evenness and approximate horizontality of this 
surface as viewed from the summit of the bluffs, and the apparent 
absence of residual hills upon it, suggest immediately that it is a 
surface of aggradation rather than one of erosion or of river plana- 
tion. Its striking parallelism, so far as the unaided eye may judge, 



1917] Merriam-Buwalda: White Bluffs of the Columbia 



263 



with the strata of the Ringold in the face of the White Bluffs, 
strengthens this idea. Unfortunately extensive observations have not 
been made on the structure of the Ringold over more than a small 
portion of the area in which it is exposed, so that it cannot be stated 
with certainty that upturning and bevelling have not occurred in 
some of its marginal areas. 

Mode of Deposition. — The available data indicate that the Ringold 
formation was deposited in a basin the walls of which were essentially 
the Yakima Range on the west, the Saddle Mountains on the north, 
and the lava plateaus on the east and south. It is probable that the 
flat area extending east from the White Bluff's and lying about five 
hundred feet above the Columbia is to be regarded as an undissected 
remnant of the aggradational surface developed at the close of the 
period of deposition, and indicates the elevation to which the basin 
was filled. 

The Columbia cuts through high ranges like the Saddle Mountains 
instead of flowing around them, and is an antecedent stream in this 
part of its course ; in pre-Ringold time its channel therefore lay 
across the area now occupied by these sediments. The presence of 
the Columbia in this region at the time the sediments were laid down, 
and the similarity of the sediments to those transported by the stream 
at the present day, make it probable that the Columbia deposited this 
formation. Whether the strata were laid down in a lake formed in 
the course of the stream, or as flood plain deposits, is not certain, 
as the limited time spent in the area did not permit an examination 
of the peripheral areas to determine the presence or absence of such 
evidence as beaches, bars, and other lacrustal features. The muddi- 
ness of the Ringold sandstones and the sandiness of the clays are, 
however, to be contrasted with the cleaner strata usually produced by 
the efficient classifying agencies of lacustral waters. The apparent 
scarcity or absence of freshwater molluscan remains, usually quite 
common in lacustral beds, and the presence at different localities of 
scattered bones of land mammals, also favor the belief that the 
deposits are largely of flood-plain origin. 

Area. — Without having mapped its boundaries, the Ringold forma- 
tion appears to the writers to occupy an area of at least 300 square 
miles, and may extend over 500 or 600 square miles. To the north 
the beds apparently reach to the lower slopes of the Saddle Mountains. 
Their eastward limit is not known, but it is certainly several miles 
to the east of the Columbia. Their southern boundary likewise has 



264 University of California Publications in Geology [Vol. 10 

not been traced. As the Ringold deposits rise about 500 feet above 
the Columbia at the southern end of the White Bluffs, and the river 
has excavated a valley several miles wide south of this point, it is prob- 
able that the beds originally extended a considerable distance down 
the river, perhaps beyond Pasco. To the west the beds appear to 
be bounded by the base of the basaltic Yakima Range, which lies at 
distances from the river ranging up to fifteen miles or more. Con- 
sidering the height to which the Ringold rises above the river in the 
White Bluffs region, it is probable that this formation originally 
extended up through the gap which the Columbia has cut across the 
Saddle Mountains, and that it was deposited over areas north of that 
range. 

More precise data concerning the areal distribution of the Ringold 
and regarding its physiographic relations will be necessary before it 
will be possible to offer a satisfactory statement of the factors which 
caused the Columbia to deposit these sediments. From general con- 
siderations it is probable that the accumulation was due: (a) to an 
uplift across the course of the Columbia at some point downstream, or 
(6) to a subsidence of the region which the Ringold now occupies, or 
(c) to a change in the relation of the detrital load of the Columbia to 
its transporting power. The last condition might be associated with 
climatic fluctuations of the Glacial period or with marked changes in 
position of the course of the Columbia which are known to have 
occurred in the hundred miles or more of its channel north of the 
Saddle Mountains. Additional field-work, which the writers hope 
to carry out during a coming season, will be required before this 
problem can be solved. 

Relation to the Ellensburg Formation. — In view of the difference 
in age between the Ellensburg and Ringold faunas it is important 
to know the stratigraphic relations of the formations in which they 
occur. It is probable that the two sets of beds come in contact on 
the western border of the Ringold, and perhaps at other points, but 
none of these localities have been examined. If the very even surface 
extending eastward from the White Bluffs be correctly interpreted as 
a remnant of the original surface of deposition, the Ringold strata 
probably lie approximately flat along the flanks of ridges consisting 
in part of folded Ellensburg strata. Such field data as have been 
obtained, taken with the palaeontologic evidence indicating difference 
in age, suggest unconformity between the two formations. 

Transmitted March 7, 1917. 



EXPLANATION OF PLATE 13 



Fig. 1. Exposures of Eingold formation in White Bluffs (loe. 2757), one 
to two miles north of Eingold, Washington. Horse teeth and bones were secured 
at point near right end of figure at horizon just above resistant layer shown half 
way up bluff. Looking north. 

Fig. 2. White Bluffs across the Columbia Biver from Hanford, Washington. 
Note evenness of skyline and parallelism of Eingold strata with crest of bluffs 
and with water surface. Height of bluffs approximately five hundred feet. 



[266] 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 16, pp. 267-286, 10 text figures Issued May 11, 1917 



STRUCTURE OF THE PES IN MYLODON 

HARLANI 

% 

BY 

CHESTER STOCK 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 16, pp. 267-286, 10 text figures Issued May 11, 1917 



STRUCTURE OF THE PES IN MYLODCW ^ < 
HARLANI 



BY 



CHESTEK STOCK 



CONTENTS 

PAGE 



Introduction 267 

Structure of pes 268 

Comparison with other mylodont genera 278 

Comparison with Lestodon 279 

Comparison with Scelidotherium 280 

Modification and specialization of pes 282 

Eelation of mylodont pes to supposed human footprints in Pleistocene strata 

at Carson City, Nevada 284 

Conclusions 285 



Introduction 

It is more than seventy years since the great British comparative 
anatomist, Richard Owen, 1 described the skeleton of Mylodon robustus 
from remains obtained in the Pampean Pleistocene of South America. 
In this masterpiece of exact observation and deduction there is included 
a discussion of the nearly complete manus and pes as they occur in that 
species. The figures 2 of M. robustus are by far the best available, 
illustrating the skeletal structure of the feet in the genus, and have 
been widely used as a basis for comparison with other mylodont 
material. 

Since the publication of Owen's memoir, information concerning 
the mylodont sloths from the North American Pleistocene has grad- 

1 Owen, R., Description of the skeleton of an extinct gigantic sloth, Mylodon 
robustus, Owen, with observations on the osteology, natural affinities, and prob- 
able habits of the megatherioid quadrupeds in general, London, 4to., 176 pp., 
24 pis., 1842. 

2 Ibid., pis. 15 and 21 (see also pis. 16 and 22), 1842. 



26S 



University of California Publications in Geology [Vol. 10 



ually accumulated and has received considerable addition within the 
past few years. Comparatively little is at present known, however, 
of the foot-structure in these forms. Fortunately the excellent and 
very abundant material of Mylodon harlani from Rancha La Brea, 
now in the palaeontological collections of the University of California 
and the Museum of History, Science and Art of Los Angeles, permits 
as complete an understanding of the manus and pes in the North 
American species as in the South American M. robustus. 

During the course of an investigation of the structure of the pes 
in Mylodon harlani, certain differences between this species and M. 
robustus have presented themselves which apparently are not of specific 
character, but are due rather to a new interpretation of the elements 
involved in the former species. As there is reason for offering an inter- 
pretation of the foot-structure differing in a few particulars from that 
of Owen, the writer has attempted to present a reconstruction of the 
pes of Mylodon based upon the assembled foot material of M. harlani 
from Ranch o La Brea. In this study Owen's description and figures 
of the pes of M. robustus have been particularly helpful. 

Structure op Pes 

In number of elements present the pes of Mylodon harlani is similar 
to that of M. robustus. It is worthy of note that in both species digit 
1 and the internal cuneiform have totally disappeared. The presence 
of claws on digits 2 and 3 and the amount of reduction which has 
occurred in the fourth and fifth digits are as characteristic of the 
North American as of the South American species. Two distinctive 
differences, among others existing between the two species (see figs. 
1 and 2), are at once noticeable in a comparative study of the pes: 

( 1 ) The relative size of the middle cuneiform and metatarsal 2 ; 
and (2) the size of the second and third phalanges of the median digit. 
These differences will be considered in greater detail below. 

Tarsus. — The posterior border of the tuberosity of the calcaneum 
is more rounding than in M. robustus. The tendinal notch on the 
external side is larger than in the South American species and opens 
rather widely, while along the inner border the calcaneum, at approxi- 
mately the middle, is much thicker dorsoventrally. The astragalus 
differs from that of M. robustus in the sharper angle between the two 
confluent articulating surfaces for the tibia. Lull 3 has described in 

s Lull, B. S., A Pleistocene ground sloth, Mylodon harlani, from Eock Creek, 
Texas, Amer. Jour. Sei., vol. 39, pp. 375-378, 1915. 



1917] Stock: Structure of the Pes in Mylodon harlawi 



26! > 



detail the astragalus and navicular of M. harlani from Rock Creek, 
Texas, and they need not be considered further at this time. In 
M. robustus the cuboid is apparently longer anteroposterior^ than 
wide, while in M. harlani the reverse is true, the cuboid being wider 
transversely than long. The outer (lower) surface of the cuboid 




Fig. 1. Mylodon harlani Owen. Left pes, outer view, X V±- Unguals slightly 
foreshortened. Bancho La Brea beds. 

Fig. 2. Mylodon robustus Owen. Left pes, X %. After Owen. Pampean 
Pleistocene beds, South America. 



articulates with a greater portion of metatarsal 5 and with a corre- 
sponding lesser portion of metatarsal 4 than in M. robustus. In the 
latter species there is a much smaller articulation of the posterior face 
with the calcaneum. This difference may also be more apparent than 
real. 



270 University of California Publications in Geology [Vol.10 



The external cuneiform does not differ essentially from the corre- 
sponding element described by Owen, but is smaller than that shown 
in the pes of M. robustus. An articular facet for the cuboid has not 
been observed on any of the specimens from Rancho La Brea, although 
some do show a facet on the inner side for the middle cuneiform. 
Owen 4 describes the latter element as follows : 

The internal of the two cuneiform bones is about half the size of the external 
one, and of nearly the same antero posterior diameter, but more compressed 
laterally, and of somewhat less depth: its convex base is uppermost; its obtuse 
apex downwards: the inner and outer sides are nearly flat, rough, without 
trace of smooth articular surface, which is limited to the anterior and posterior 
extremities of the bone. The posterior surface is elliptical, slightly concave, 
adapted to the distinct circumscribed articular surface on the naviculars: the 
anterior articular surface is nearly circular, and very slightly convex. There is 
no articular surface upon the tibial or inner side of this cuneiform bone, nor any 
indication of a third or internal cuneiform on the os naviculare; from which it 
is to be concluded that the internal cuneiform bone and first toe, or hallux, were 
altogether wanting in the Mylodon, and that the mutilation by which its hind- 
foot is reduced to the tetradaetyl type has commenced, according to the ordinary 
law, from the inner side. 

In Mylodon harlarri the middle cuneiform is compressed laterally 
and is roughly wedge-shaped (figs. 3b and 5) with the anteroposterior 
diameter of the rounded and narrow dorsal surface twice as great as 
the corresponding diameter ventrally. The depth of the cuneiform 
may be greater or less than the greatest anteroposterior diameter. The 
ventral surface is flattened and is wider transversely than the dorsal 
surface. The outer surface is flatter than the inner and, in all the 
specimens examined, bears along the proximal margin a facet for the 
external cuneiform. There is no indication of a facet along the proxi- 
mal margin of the inner side for an internal cuneiform. The proximal 
articulating surface for the navicular is rectangular in shape and is 
slightly concave. At the distal end the articulating surface for the 
metatarsal is placed oblique to the vertical axis of the cuneiform. It 
is of greater dorsoventral diameter than the proximal articulation and 
is more deeply concave in that direction. The surface narrows dor- 
sally and in most specimens is constricted at about the middle of the 
internal side. The middle cuneiform is noticeably larger than in 
M. robustus. 

Metatarsus. — The second metatarsal in M. robustus is described by 
Owen 5 as follows : 



4 Owen, op. ext., p. 121. 

5 Owen, op. cit., p. 121. 



1917] Stock: Structure of the Pes in Mylodon harlani 



271 



... a moderately long, subcompressed bone, having its proximal end ob- 
liquely truncated, and supporting a circular and nearly flat surface, below which 
there is a rough tuberosity. A narrow vertical channel with a large perforation 
in the middle, and with a convexity before and behind, characterizes the outer 
side of this bone; its inner side is rough and similarly unequal: on neither side 
is there the least trace of an articulation with an adjoining metatarsal. The 
distal end presents a simple ovate articular convexity, with the small end upwards. 

As shown by Owen's figures, metatarsal 2 is fully twice as long 
as the cuneiform with which it articulates. 

In Mylodon harlani the second metatarsal differs decidedly from 
that of M. robustus in its relative length. This element, as contrasted 
with M. robustus, is exceedingly short anteroposteriorly, often shorter, 




Figs. 3a and 36. Mylodon harlani Owen. Middle cuneiform and second meta- 
tarsal, no. 22771, X Eancho La Brea beds. Fig. 3a, superior view; fig. 3b, 
inner view. 

Figs. 4a and 4b. Mylodon harlani Owen. Co-ossified middle cuneiform and 
second metatarsal, no. 22772, X %. Eancho La Brea beds. Fig. 4a, superior 
view; fig. 4b, inner view. 

in fact, than the middle cuneiform in M. harlani. In the marked 
shortening of metatarsal 2, the pes of the latter species may be con- 
strued as being more advanced than that of M. robustus. It is to be 
noted, however, that the middle cuneiform is relatively longer in 
M. harlani than in M. robustus. 

The proximal and distal articulating surfaces of the second meta- 
tarsal may almost meet dorsally, giving the element a triangular shape 
in side view. In some specimens the proximal face is almost vertical 
and the metatarsal therefore approximates a quadrilateral form. The 
proximal articulating surface conforms in outline to the distal artic- 
ulating surface of the cuneiform and may be convex below and slightly 

o Ibid., pis. 21 and 22. 



272 



University of California Publications in Geology [Vol. 10 



concave above. The distal articulation is elongate dorsoventrally, con- 
vex, and faces upward and slightly inward. The lower margin of the 
surface is straight. The inner side of the metatarsal is convex dorso- 
ventrally, while the outer side, as in M. robustus, bears a narrow 
vertical groove, which joins below an excavation between the proximal 
and distal extremities. 

A single specimen, no. 22772, representing a fusion of the middle 
cuneiform and metatarsal 2 in the pes of M. harlani, occurs in the 
collections at the University of California from the asphalt beds. All 
indications of an original separation are obliterated, although the two 
elements are easily recognized by their otherwise characteristic shape 
(contrast tigs. 3(7, 3b, and 4a, 46). Along the proximal margin of 
the outer side in no. 22772 there is no distinct facet for the external 
cuneiform. The specimen is of special interest in its great similarity 
to Owen's figure and description of metatarsal 2 of M. robustus. 7 It 
suggests, at least, that in the latter species the second metatarsal as 
determined by Owen may possibly be the homologue of no. 22772 from 
Rancho La Brea. 8 

In M. harlani the third metatarsal articulates with more of the 
oblique proximal face of metatarsal 4 than in M. robustus, reaching 
half way across this face. The fourth metatarsal may be slightly 
longer than in the South American species. In the fifth metatarsal 
the large and heavy lateral process of the proximal end is well formed. 
It projects outward and backward more from the side of the meta- 
tarsal than in M. robust us, resembling in this respect Scelidotherium. 
M. harlani further agrees with the latter genus and differs from M. 
robustus in that the fifth metatarsal does not touch the calcaneum. 
It is possible, however, that in M. robustus some of these characters 
may be subject to intraspecific variation. 

Digits. — Mylexlon harlani agrees with its South American contem- 
porary in the loss of the first digit, the presence of claws on digits 2 
and 3, and the amount of reduction suffered by the fourth and fifth 
digits. 

The second digit, as in M. robustus, consists of two elements. 

i Owen, R., op. cit., pis. 21 and 22. See also his description quoted above. 

8 Dr. W. D. Matthew, who very kindly examined for the writer the mylodont 
foot material in the American Museum of Natural History, states that the 
middle cuneiform in the feet of Mylodon in which it is preserved is much shorter 
than the second metatarsal. In this respect the second metatarsal agrees with 
Owen 's figure, but the middle cuneiform appears to have a different shape. 
Dr. Matthew notes further that in the specimen of Lestodon the middle cunei- 
form and second metatarsal are co-ossified. 



1917] 



Stock: Structure of the Pes in Mylodon harlani 



273 



Fusion of the first and second phalanges has given rise to a single 
element, which is similar in shape to its homologue in the first digit 
of the manus, but is somewhat heavier and larger. Similarly the 
ungual is larger and heavier than the corresponding phalanx in digit 
1 of the manus. The claw process of the ungual points inward. 




Pleistocene beds at Carson City, Nevada. 

The height of the first phalanx of digit 3 is slightly greater than 
the basal width. The phalanx narrows but little dorsally from the 
base, agreeing in this character with the same phalanx in M. robustus 
and differing from the corresponding phalanx in digit 2 of the manus 
in the latter species and in M. harlani. It differs further from the 



274 



University of California Publications in Geology [Vol. 10 



first phalanx of digit 2, manus of M. harlani, in the much shorter 
anteroposterior diameter. This is due to the flatness of the two artic- 
ulating condyles on the distal face for phalanx 2, and to the more 
shallow proximal concavity. The latter concavity, which receives the 
convex distal carina of the third metatarsal, narrows below. Along 
almost the entire inner side of this concavity is an offset which widens 
below, while at the lower end of the outer side a small offset is also 
present. In M. robustus Owen describes the proximal face of the 
phalanx as "concave, adapted to the upper two-thirds of the convex 
trochlea of the metatarsal bone, and widening as it descends. ' ' Below 
each offset and on the ventral surface are two small facets for the 
sesamoids. Between these the ventral margin of the phalanx is broadly 
concave. 

As interpreted by Owen, the characteristic features of the second 
phalanx, digit 3, of the pes of M. robustus and the corresponding 
phalanx of digit 2, manus, may be briefly tabulated as follows : 



Phalanx 2, Digit 2, Manus 

(1) Long in proportion to its 
breadth, which is greatest in the ver- 
tical diameter of its base. 

(2) Proximal articulation concave 
vertically, traversed by a median ob- 
tuse ridge. 

(3) Distal articulation describes a 
semicircle. 



Phalanx 2, Digit 3, Pes 

(1) Anteroposterior diameter ex- 
ceeds by one-eighth part the vertical 
diameter, and by one-third part the 
transverse diameter. 

(2) Proximal articulation consists 
of two vertical concavities separated 
by a median ridge. Upper extremity 
of latter ridge more produced than 
lower. 

(3) Convex borders of distal troch- 
lea describe two-thirds of a circle. 



In dimensions and in structure of distal trochlea, the second 
phalanx of digit 3, pes of Mylodon harlani, differs from the corre- 
sponding phalanx of the pes of M. robustus and agrees more closely 
in these characters with phalanx 2, digit 2, manus of the latter species. 
This difference from Owen's interpretation is distinctly brought out 
also by a comparison with his figures (see figs. 1 and 2, also Owen, 
pi. 15). The depth of the proximal end of the second phalanx may 
be slightly less than or may exceed the total length of the phalanx in 
M. harlani. The second phalanx is often only half as large as the 
corresponding phalanx in the second digit of the manus. The proxi- 
mal face is broad at the base and narrows dorsally to a posteriorly 
projecting process approximately one-half of the basal width. Some 

s Owen, op. ext., p. 123. 



191"] Stock: Structure of the Pes in Mylodon harlani 



275 



similarity to the corresponding phalanx of M. robustus, as interpreted 
by Owen, is thus shown by the backward projection of the dorsal 
end of the median ridge. The two flattened articulating surfaces of 
the proximal end are much less deeply excavated than in the corre- 
sponding phalanx of digit 2 of the manus. The articulation between 
the first and second phalanges allowed but little vertical movement. 
The external convexity of the distal trochlea has a greater depth than 
the internal, and its articulating surface is flatter. A certain amount 
of compensation for the outward twisting of metatarsal 3 is obtained 
through the articulations of the first and second phalanges, which tend 
to allow the ungual to play in a more nearly vertical direction. 



Figs. 7a and 7b. Mylodon harlani Owen. First and second phalanges, third 
digit of pes, no. 22769, X %. Kancho La Brea beds. Fig. 7a, superior view; 
fig. 7b, outer view. 

Figs. 8a and 8b. Mylodon harlani Owen. Co-ossified first and second pha- 
langes, third digit of pes, no. 22770, X %. Bancho La Brea beds. Fig. 8a, 
superior view; fig. 8b, outer view. 

Among the materials representing digit 3 of the pes of Mylodon 
harlani there are several specimens which were evidently formed by 
co-ossification of first and second phalanges (compare figs, la, lb with 
8a, 8b). The fused element is always somewhat shortened proximo- 
distally. A similar co-ossification occurs in the third digit, pes, of 
Megatherium, Megalonyx, and Nothrotherium, though it is worthy 
of note that in the Miocene genus Hapalops the two phalanges are 
separate. Among the Mylodontidae the same structure obtains in 
C atony x and Scelidotherium, but the co-ossified element is broader 
and more fore-shortened than the Rancho La Brea specimens. The 
two phalanges are separate in Lestodon, Pseudolestodon, 10 and in 
Mylodon robustus. The lack of any great movement between the 

io Bautenberg, M., Ueber Pseudolestodon hexaspondylus, Palaeontographica, 
Bd. 53, s. 1-50, 6 taf., 1906. This genus is considered by Lydekker as syn- 
onymous with Mylodon, by other authors with Lestodon. 




7b 



7a 



8a 



8b 



276 University of California Publications in Geology [Vol. 10 



separate phalanges, together with the location of principal vertical 
movement between the first phalanx and the metatarsal in Mylodon, 
may be in part conducive to such co-ossification. It is more probable, 
however, that the co-ossification of the two phalanges in the genera 
cited above is to be correlated with the large ungual of the median 
digit, which prevails in these forms and requires a rigid support, while 
in Mylodon the relatively much smaller third ungual is accompanied 
by a more loosely articulating digit. Fusion of the two phalanges 
in M. harlani may depend upon the age of the individual. 

In the identification of the foot material of Mylodon garmani, 
Dr. G. M. Allen, 11 who of necessity has followed Owen's determinations 
for M. roiutus, has assigned to the second digit of the manus of 
the former species an element which is evidently identical with the 
structure under consideration. Allen 12 states : 

The phalanx next, proximal to this [referring to the ungual of digit 2] is 
short, 53 mm. long, with two rounded facets anteriorly, and a broadly concave 
facet posteriorly. On each side of the latter, at its ventral corners, is a small 
squarish facet which evidently articulated with a sesomoid. 

The character of the proximal and distal ends and the length of 
tlie phalanx establish its identity as the homologue of the co-ossified 
first and second phalanges in the third digit of the pes of M. harlani. 

Characteristic features exhibited by the ungual of digit 2, manus, 
and digit 3, pes, of M. robust us as interpreted by Owen may be 
tabulated as follows : 

Ungual, Digit 2, Manus Ungual, Digit 3, Pes 

(1) One half the dimensions of un- (1) Judging from figures, ungual 
gual of digit 3, manus. much larger than that of digit 2, 

manus, and approaching terminal pha- 
lanx of digit 3 in size. 

(2) Backward production of the (2) In extreme extension, long axis 
upper part of the proximal joint per- may be parallel with that of second 
mits claw-bone to be bent only down- phalanx. 

wards. 

(3) Broad, rough, quadrilateral base (■'!) Flat, rough, oval surface at the 
of claw-sheath. proximal half of base of claw. 

(4) Claw-process conical, nearly (4) Claw-process forms chief part 
straight, with an oblique base which of ungual, conical, slightly deflected, 
gives under only half the length of inclined inwards. Under surface, ow- 
the upper part. ing to oblique line from which sides 

of ungual sheath arise, is less than 
half the length of the upper surface. 



11 Allen, G. M., A new Mylodon, Mem. Mus. Comp. Zoiil. Harv. Coll., vol. 40, 
pp. 319-346, 4 pis., 1913. 
1= Ibid., p. 336. 



1917] 



Stock: Structure of the Pes in Mylodon harlani 



277 



Ungual, Digit 2, Manus — 



Ungual, Digit 3, Pes — 



(Continued) 



(Continued) 



(5) Upper part of claw-process pre- 
sents regular convexity from side to 
side, flattened toward apex, and di- 
vided by two sharp edges from less 
convex under surface. 



(5) Claw-process convex above and 
at the sides; under surface convex 
transversely along its middle part, 
concave on each side. Claw-process 
for the extent of one inch and a half 
from its apex is impressed above with 
a shallow longitudinal groove. 



A comparison of the characters presented by the ungual, digit 3, 
pes of M. harlani, with those above listed at once brings out a closer 
agreement, especially in size, with the ungual, digit 2, manus, than 
with the ungual, digit 3, pes, of M. robustus as interpreted by Owen. 

The conclusion, therefore, seems inevitable that in Owen's recon- 
struction of the pes, as figured on plates 21 and 22 of the memoir on 
Mylodon robustus, the second and third phalanges of digit 3 have 
been interchanged with the corresponding phalanges of digit 2 of the 
manus. So far as is known to the writer, Owen's interpretation of 
these structures in Mylodon robustus lias never been questioned. 13 
Rautenberg, 14 in a study of the greater part of a skeleton of 
Pscudolestodon, describes and figures the pes and manus of that form. 
Although he recognizes the terminal claw of the third digit of the 
pes as the third largest of the ungual series, lie has not noted the 
significance of this character when contrasted with M. robustus. In 
comparing the feet of Pscudolestodon with M. robustus Rautenberg 15 
states : 

Die Fussknochen bieten bei den beiden zum Vergleich herangezogenen Gravi- 
graden nur geringe Abweichungen. Hervorzuheben ware, dass der Calcaneus 
bei Mylodon etwas kiirzer imd weniger breit erscheint, und dass die zweite und 
dritte Zehe bei Pseudolestodon nicht ganz die Grossenverhaltnisse des Mylodon 
erreieht. 

Again, in comparing the manus Rautenberg"' writes as follows: 

. . . Ganz besonders in die Augen fallend ist die Grossenzunahme des zweiten 
und dritten Fingers, dessen fast gleichlange Krallen die ubrigen inn das Drei- 

13 During the course of completion of this paper the writer learned from 
Dr. W. D. Matthew that the changes necessitated by this new interpretation 
were already made in the mount of Mylodon robustus in the American Museum 
of Natural History. Mr. J. Z. Gilbert, who has studied the manus of Mylodon 
harlani from Eancho La Brea, reaches the same conclusion (MS. in press) from 
an interpretation of the second digit of the hand. 

14 Rautenberg, M., Ueber Pseudolestodon hexaspondylus, Palaeontographica, 
Bd. 53, s. 1-50, 6 taf., 1906. 

15 Rautenberg, M., op. cit., p. 40. 
i« Ibid., p. 41. 



278 



University of California Publications in Geology [Vol. 10 



fache iibertreffen. Bei Mylodon ist einerseits die Kralle des zweiten Fingers 
nor halb so lang wie die des dritten, andererseits ist sie aber absolut kiirzer als 
die entspreehende am Hinterfuss. 

In the light of the new interpretation here presented of digit 3, 
pes of Mylodon, the ungual determined by Allen 17 as belonging to the 
second digit of the manus of M. garmani should be regarded as of 
digit 3, pes of that species. The ungual which has been determined 
as of the third digit of the pes by Dr. Allen, 18 following Owen, belongs 
to the second digit of the manus. 

Digits 4 and 5 have suffered the same amount of reduction in 
M. harlani as in M. robust us. The first phalanx of digit 4 resembles 
in size the corresponding phalanx of digit 3, but differs greatly from 
the latter in general shape and in the nature of the proximal and distal 
articulating faces. The proximal face presents a vertical concavity 
to conform with the distal end of the metatarsal. Bordering the 
lower half of the inner margin of the proximal concavity and con- 
fluent with it is an articulating offset. The ventral margin of the 
phalanx below the concavity is notched and bears on each side a small 
facet for a sesamoid. The distal articulating face has been shifted 
inward, causing the first phalanx to be decidedly oblique with reference 
to a median vertical plane. This surface is concave transversely and 
of greatest depth along the inner side. Accompanying the obliquity 
of the phalanx is the greater length of the outer side, which is twice 
that of the inner. 

The fifth metatarsal in M. harlani bore at the distal end a nodular 
rudiment, which in turn articulated distally with a much smaller 
element, as in M. robust us. 

Comparison With Other Mylodont Genera 
In the following comparison of the pes of Mylodon harlani with 
that of other mylodont genera, it is desired at present only to indicate 
such of the contrasting features as may be seen in the complete foot- 
structure of these forms. The comparative study of the pes of 
Lestoclon armatus by Gervais 10 has been of much value in this con- 
nection, while the description of the foot-structure in Scelidotheriuni 

i- Allen, G. M., op. cit., p. 336, pi. 3, fig. 9. 

is Ibid., p. 340, pi. 3, fig. 12. This interpretation of the unguals of M. garmani 
is also held by Mr. J. Z. Gilbert. 

1 » Gervais, P., Memoire sur plusieurs especes de mammiferes fossiles propres 
a l'Amerique Meridionale, Mem. Soe. Geol. France, Ser. 2, T. 9, Mem. 5, pp. 21-35, 
pis. 5-7 (pis. 25-27), 1873. 



1917 ] Stock: Structure of the Pes in Mylodon hqrlani 279 



leptocephalum by Burmeister, 20 and his compai'isons with Mylodon 
and Megatherium, have been of greatest assistance. Reference should 
also be made to Owen's earlier observations 21 on Scelidotherium. 

COMPAEISON WITH LESTODON 
The calcaneum in M. harlani differs from that in Lcstodon in its 
greater constriction below the astragalus, and in the less broadly 
rounded posterior end. The tendinal groove on the outer border of 
the calcaneum is much better developed in M. harlani. An important 
difference between the two genera in the calcaneum, to which attention 
has been directed by Gervais, but which is not apparent in a com- 
parison of the figures of the mounted pes of these forms, is the division 
of the astragalar facet. In this respect Lestodon is more like the 
Megalonychidae. Gervais also points out that in general shape the 
calcaneum of Lestodon is more like the corresponding element in 
Megatherium. In Mylodon harlani the angle between the inner and 
outer divisions of the tibial articulating surface of the astragalus is 
smaller than in Lcstodon. Judging from Gervais' figure 22 of the pes 
of L. armatus, the outer or fibular side of the astragalus is not as deep 
as in M. harlani. 

The navicular in the Rancho La Brea species is less compressed 
than in Lcstodon, and the external cuneiform is thicker in the latter. 
In the latter also the middle cuneiform and the second metatarsal are 
fused, while in M. harlani these elements are usually separate. Gervais 
states that the third metatarsal is relatively much longer than in 
Mylodon. 

In structure and size the second and third digits in the pes of the 
species from the asphalt are very close to Lestodon. The second digit 
is composed of two elements, the proximal one of which is a composite 
structure as in the latter. Digit 3 is composed of three elements ; the 
two proximal phalanges are as a rule not co-ossified. In Lestodon 

20 Burmeister, H., Bericht iiber ein Skelet von Scelidotherium leptocephalum, 
Monatsberichte Akad. Berlin, pp. 374-381, 1 pi., 1881. 

21 Owen, E., Description of a considerable part of the skeleton of a large 
edentate mammal, allied to the Megatherium and Orycteropus, and for which is 
proposed the name of Scelidotherium leptocephalum. The zoology of the vovage 
of H. M. S. Beagle, etc., pt. 1, Fossil Mammalia, pp. 73-99, pis. 20-23, pi. 24, 
fig. 1, pi. 25, pi. 26, figs. 2, 4, and 6, pi. 27, pi. 28, fig. 2, 1840. 

Owen, E., Description of the skeleton of an extinct gigantic sloth, Mylodon 
robustus, etc., pp. 126-137, 1842. 

Owen, E., On the Megatherium (Megatherium American um, Cuvier and Blu- 
menbach). Pt. V. — Bones of the posterior extremities, Philos. Trans. Boy. Soc. 
London, vol. 149, pp. 821-823, 1859. 

22 Gervais, P., op. tit., pi. 7, fig. 6, 1873. 



280 University of California Publications in Geology [Vol. 10 



there is uo fusion of these phalanges. The ungual of this digit is 
comparable in size with that of Lestodon, and thus both agree in 
differing from Megalonyx and Scelidotherium. 

The fifth metatarsal in Lestodon resembles that of M. robustus 
rather more closely than that of M. harlani in flatness of the outer 
side. The fourth and fifth digits in M. harlani have suffered a re- 
duction similar to that in Lestodon. 

COMPARISON WITH SCELIDOTHERIUM 

Burmeister states that the calcaneum in Scelidotherium approaches 
in shape the genera Megalonyx and Nothrotherium rather than Mega- 
therium and Mylodon. Owen had previously pointed out that "In 
the Scelidotherium the posterior termination of the calcaneum is 
broader, and terminated by a less angular convexity than in the 
Mylodon. . . . " 23 In the thickness of the tuber calcis Scelidotherium 
is more like other mylodonts and differs from Megalonyx and Nothro- 
tlu rium, in which the posterior portion of the calcaneum is compressed 
and fan-shaped. With regard to the second largest of the ankle bones 
Owen states: "The astragalus of the Scelidotherium agrees with that 
of the Mylodon in the less depth of the middle division of the upper 
surface and the more open angle at which it joins the inner convexity. 
. . . " 24 It has already been pointed out 23 that the inner and outer 
divisions of the tibial articulating surface of the astragalus are sep- 
arated by a more distinct angle in M. harlani than in M. robustus. 
The astragalus in Scelidotherium magnum, as shown by Winge, 20 is 
unquestionably more nearly like that in members of the Mylodontidae 
than that in the Pleistocene Megalonychidae. In the less open angle 
between the confluent articulating surfaces for the tibia the astragalus 
of this form resembles Mylodon harlani more closely than M. robustus. 

In the pes of Scelidotherium magnum as given by Winge, 27 the 
internal and middle cuneiforms, with the former of which the first 

23 Owen, R., On the Megatherium, etc., p. 822. See also Owen, Description of 
the skeleton of an extinct gigantic sloth, Mylodon robustus, etc., p. 133. 

Ibid., p. 821, 1859. See also Owen, Description of the skeleton of an ex- 
tinct gigantic sloth, Mylodon robustus, etc., p. 132. 

25 P. 269. 

20 Winge, H., Jordfunde og nulevende Gumlere (Edentata) fra Lagoa Santa, 
Minas Geraes, Brasilien. Med Udsigt over Gumlernes indbyrdes Slaegtskab, 
E. Museo Lundii., Bd. 3, pt. 2, pis. 41 and 42, Copenhagen, 1915. 

27 Winge, H., ibid., pp. 205-208, pi. 42, 1915. 



1917] 



Stock: Structure of the Pes in Mylodon harlani 



281 



metatarsal is considered to be fused, and metatarsal 2 are present as 
separate elements. It is probable, therefore, that in Burmeister's 
figure the fused element represents more than the internal cuneiform 
and the remnant of digit 2. In Mylodon liarlani the internal cunei- 
form has not been observed and from all appearances seems to have 
disappeared with the first digit. The additional loss of a functional 
second digit in SceUdotherium indicates a greater specialization in the 
pes than in M. liarlani. 

In discussing the relation of the cuneiforms to the adjoining meta- 
tarsals Burmeister states : "... bei Mylodon nur ein einziges, grosses 
cuneiforme sich findet, an welches die Metatarsusknochen von drei 
Zehen (I, II, III) stossen." 28 This is certainly not the case in M. 
harlani and, as shown by Owen, in M. robustus also, where the external 
and middle cuneiforms are separate elements supporting the third and 
second metatarsal respectively. That peculiar fusion of various 
bones of the pes is apt to occur is well shown in one of the skeletons 
of Mylodon robustus in the American Museum of Natural History, in 
which, according to Dr. Matthew, the external cuneiform is co-ossified 
with the third metatarsal. 

In the marked widening and shortening of the third metatarsal 
and the presence of a heavy proximal segment in the digit which 
supports distally a very large ungual, SceUdotherium is decidedly 
different from M. harlani and is strongly suggestive of the Pleistocene 
Megalonychidae. The large ungual in SceUdotherium is supported by 
the co-ossified first and second phalanges, while in Mylodon the cor- 
responding ungual is much smaller and is supported by first and 
second phalanges, which are usually separate. In the slender fourth 
metatarsal of the former genus the articulating faces for cuboid and 
metatarsal 3 are separated by a distinct angle, while in M. harlani 
they are continuous in the same plane. In SceUdotherium the three 
phalanges of digit 4 are represented. The proximal and middle 
elements have co-ossified, while the distal or terminal phalanx is rudi- 
mentary. In M. harlani only two segments of this digit are present, 
but the middle or second phalanx has not become fused with the 
proximal element. The reduction of the fourth digit in SceUdotherium 
is, therefore, not as advanced as in Mylodon. Burmeister believes 
that a closer agreement of SceUdotherium with Megatherium than with 
Mylodon is shown in that "die beiden Metatarsusknochen der zwei 
ausseren Zehen nur am cuboideum gelenken, und nicht, wie bei 

28 Burmeister, H., op. cit., p. 380. 



282 University of California Publications in Geology [Vol. 10 



Mylodon, der ausserste zugleieh noeh den calcaneus beriihrt." 20 In 
M. harlani the fifth metatarsal agrees more closely in shape with 
SceUdotheriwm than with M. robustus, and does not touch the cal- 
caneum as in the latter species. 

It is now generally conceded that Scelidotherium is a member of 
the Mylodontidae, a fact which is especially shown by the lobate 
character of the teeth. The present observations on the pes indicate 
that, with due allowance for variations in the individual elements of 
both genera, certain resemblances between Mylodon and Scelidothe- 
rium, are closer than was supposed by earlier authors. Associated 
with these characters are modifications in Scelidotherium which remind 
one strongly of other Gravigrada. 

Modification and Specialization op Pes 

The twisting of the pes in Mylodon harlani, which brings the 
weight of the body to bear mainly upon the outer side of the foot, has 
profoundly affected the morphological structure. It has brought 
about a number of adaptations suited to a highly specialized type of 
locomotion. Several of the peculiar modifications to be noted in the 
pes of Mylodon harlani, some of which are of family, others of generic, 
distinction, may be listed as follows: 

( 1 ) Large and heavy calcaneum ; 

( 2 ) Distinct angle between the confluent outer and inner divisions 
of the tibial articulating surface of the astragalus; 

(3) Broadening and flattening, especially of the outer, posterior 
portion, of metatarsal 5 ; 

(4) Reduction suffered by the fourth and fifth digits; 

(5) Abbreviation of digit 3, with a much smaller ungual than in 
the corresponding digit of the manus ; 

(6) Abbreviation of the second digit and metatarsal, with which 
is associated a much smaller ungual than in the corresponding digit 
of the manus ; 

(7) Loss of digit 1 and the internal cuneiform. 

One of the important modifications of the pes, lending itself to 
a comparative study, is that shown by the astragalus. In a de- 
scription of the ground-sloths from the Santa Cruz Miocene deposits 
of Patagonia Scott has referred to Nematherium an astragalus which 



-'■> Burmeister, H., op. cit., p. 380. 



1917] Stock: Structure of the Pes in Mylodon harlani 



283 



he states 30 is "quite similar to that of the Megalonychidae, but a 
marked and suggestive likeness to Mylodon is seen in the trochlea; 
the inner condyle has a very distinct tendency to assume the odontoid 
shape and is much less extended proximo-distally than the external 
condyle." It is worthy of note that Scott considers the astragalus 
of Prepotherium as approaching that of Megatherium in the proximo- 
distal shortness and strong convexity of the tibial articulating surface 
and its prominent inward projection. Scott believes that in Prepo- 
therium these characters indicate "a beginning had been made in the 
rotation of the foot, so as to bring the weight upon the fibular border. ' ' 
The pronounced development of the odontoid, inner division of 
the tibial articulating surface of the astragalus in M. harlani, and the 
distinct separation between it and the outer division in the Rancho 
La Brea species indicate a greater specialization than in Megalonyx 
and Nothrotherium. It represents the result of a differentiation which 
had already commenced in the Miocene. The extreme modification 
of the astragalus in Mylodon would seem to suggest that the weight 
of the body was often supported by the posterior limbs alone. This 
is in accord with Owen's conception of the form as a browsing type, 
often resting its weight on the posterior extremities while using the 
anterior limbs to bring branches and foliage of trees within reach of 
the mouth. 

Allowing for the new interpretation of the second and third pha- 
langes of digit 3, the pes of Mylodon harlani is close in stage of 
evolution to that of M. robust us. In the distinct angle between the 
divisions of the tibial articulating surface of the astragalus, M. harlani 
is more advanced than the type of M. robustus as figured by Owen. 
This character is, however, somewhat variable in the North American 
species. A greater degree of advancement in M. harlani is suggested 
by the anteroposterior shortening of metatarsal 2, and the greater 
anteroposterior extension of the middle cuneiform than in M. robustus. 

The co-ossification of the first and second phalanges of the median 
digit is characteristic of Megatherium, Megalonyx, Nothrotherium, 
and, among the Mylodontidae, of Scelidotherium and Catonyx. Fusion 
of the two phalanges has been noted in Mylodon garmani and may 
occur in M. harlani, but is apparently absent in M. robustus. In 
Lestodon and Pseudolestodon the two phalanges are separate. The 
widespread occurrence of this co-ossification among Pleistocene Gravi- 

30 Scott, W. B., Eeports of the Princeton University Expedition to Patagonia, 
1896-1899, vol. 5, pt. 1, Edentata, 3, Gravigrada, p. 350, 1904. 



284 University of California Publications in Geology [Vol. 10 



grada is a distinctly more advanced character than the separation of 
the phalanges in the Miocene gronnd-sloths from the Santa Cruz beds. 
In the Pleistocene forms in which the co-ossification habitually occurs 
a large median ungual is present, while in Mylodon, where the first 
and second phalanges are usually separate, the ungual is tending to 
become reduced. The co-ossification of the two phalanges noted in 
M. harlani is presumably secondary and may be an age characteristic. 

In M. harlani only two elements of the fourth digit are present, 
while in Scelidotherium the three phalanges are represented, the first 
and second having co-ossified and the third being rudimentary. In 
this respect Mylodon harlani is more advanced than Scelidotherium. 

Relation of Mylodont Pes to Supposed Human Footprints in 
Pleistocene Strata at Carson City, Nevada 

Occurrence of fossil footprints in Pleistocene strata at ("arson, 
Nevada, first attracted scientific attention some thirty-five years ago. 
The imprints were uncovered in working the stone quarries of the 
Nevada State Prison. Joseph LeConte 31 in a description of these 
footprints states : 

The whole surface of the shale exposed in the prison yard is literally covered 
with tracks of many kinds, but the mud was so soft when the tracks were made 
that the nature of many of them can only be guessed. Some were probably 
those of a horse; some probably of a wolf; some certainly of a deer; many were 
those of long legged wading birds. But the most interesting are those of the 
mammoth and the problematical so-called human tracks. 

The sitpposed human footprints referred to by LeConte measured 
18-20 inches in length and 8 inches in breadth. These tracks, occur- 
ring in associated right and left series, appeared to have been formed 
by a bipedal creature. They were considered by Harkness 82 to be 
impressions of the sandaled foot of primeval man. This belief created 
not a little discussion 33 at the time of its presentation. LeConte, 34 
however, pointed out certain obvious objections to this interpretation, 
namely, the large size and the shape of the individual imprint and 

si Letter to Nature, vol. 28, pp. 101-102, 1883. 

32 Harkness, H. W., Footprints found at the Carson State Prison, Proc. Calif. 
Acad. Sci., 7 pp., 5 diagrams, August 7, 1882. 

3S A delightful sketch written by the great American humorist, Mark Twain, 
on the ' ' human ' ' footprints at Carson, was published in The San Franciscan, 
February 16, 1884. 

34 LeConte, J., On certain remarkable tracks found in the rocks of Carson 
quarry, Proc. Calif. Acad. Sci., 10 pp., August 27, 1882. 



1917] Stock: Structure of the Pes in Mylodon harlani 



285 



the span of the straddle as measured hy the distance between right 
and left imprints. He considered the possibility that the tracks had 
been made by a bear or by a ground-sloth. In an addendum to the 
paper already referred to, LeConte mentions the suggestion of Marsh, 
that the supposed human imprints were perhaps formed by a ground- 
sloth, either Mylodon or Morotherium. 35 At that time remains of the 
latter forms were known to occur in Great Basin deposits of same 
age as the Carson strata. Marsh''" compared the imprints with the 
pes of Mylodon and expressed an opinion in favor of their association. 

The objections to the quadrupedal origin of the footprints were 
stated by LeConte to rest in "the apparent singleness of the tracks, 
and the absence of claw-marks." The first of these he explained by 
the observed fact that the imprint of the posterior foot is often super- 
imposed upon that of the anterior foot, while he attributed the second 
peculiarity to "the clogging of the feet with mud." 

From the present reconstruction of the pes of Mylodon, it is seen 
that the third digit did not bear a large claw as supposed by Owen. 
It follows that the possibility of obtaining a distinct impression of 
this claw is therefore also reduced. A comparison between the pes of 
Mylodon harlani from Rancho La Brea and the debatable footprints 
at Carson City (see figs. 5 and 6) reveals a remarkable similarity in 
size and general outline. This evidence is then in strong confirmation 
of the view expressed by LeConte and Marsh. 

The common occurrence of M. harlani in Pleistocene deposits of 
North America makes it not improbable that the imprints at Carson 
belong to an individual of this species. The possibility remains, 
however, that the footprints were made by a ground-sloth other than 
Mylodon. Megalonyx and Nothrotherium are known to have been 
present in the Sierran region during the Pleistocene. 

Conclusions 

In the restoration of the pes of Mylodon harlani, based upon 
material from Rancho La Brea, the second and third phalanges of 
digit 3 are identified Math the corresponding phalanges of digit 2, 
manus of M. robustus, as interpreted by Owen. In Owen's recon- 
struction of M. robustus the second and third phalanges of digit 2, 

35 This genus, as defined by Marsh, has been shown by the writer (Seience, 
n. s., vol. 39, pp. 761-763, 1914) to be in part synonymous with Mylodon. 

38 Marsh, O. C, On the supposed human footprints recently found in Nevada, 
Amer. Jour. Sei., ser. 3, vol. 26, pp. 139-140, 1883. 



286 University of California Publications in Geology [Vol. 10 

manus, have undoubtedly been interchanged with the corresponding 
phalanges of digit 3, pes. 

A comparison of the pes of Mylodon harlani with that of Scelido- 
therium indicates certain resemblances between the two genera, which 
support their family relationship already suggested by the lobate 
character of teeth. In contrast to Mylodon, in which the first or 
inner digit is lost, the pes of Scelidotherium is markedly more special- 
ized in the additional loss of a functional second digit. The latter 
genus differs further from Mylodon in the large size of the third 
ungual, agreeing in this character with other members of the Gravi- 
grada, as, for example, Megalonyx and Megatherium. 

The rotation of the pes toward the outer side has progressed much 
further in Mylodon harlani than in any of the Miocene ground-sloths 
from the Santa Cruz beds. This process is accompanied by a number 
of modifications adapted to a highly specialized type of locomotion. 

With allowance for the differences in interpretation, the stage of 
evolution of the pes in M. harlani is near to that of M. robustus. 

In size and general outline the pes of Mylodon harlani is remark- 
ably similar to the supposed human footprints occurring at Carson, 
Nevada. 



Transmitted December 15, 1916. 



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Volume 2, 1896-1902, 457 pp., with 17 plates and 1 map, price : $3.50 

Volume 3, 1902-1904, 482 pp., with 51 plates, price $3.50 

Volume 4, 1905-1906-, 478 pp., with 51 plates, price : $3.50 

Volume 5, 1906-1910, 458 pp., with 42 plates, price $3.50 

A list of titles in volumes 1 to 5 will be sent upon request. 



VOLUME 6. 

1. The Condor-like Vultures of Raneho La Brea, by Loye Holmes Miller 15a 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part I. — Geologic History 50c 

3. The Geology of the Sargent Oil Field, by William F. Jones 25c 

4. Additions to the Avifauna of the Pleistocene Deposits at Fossil Lake, Oregon, by 

Loye Holmes Miller 10c 

5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe, by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of Rancho La Brea, by John C. 

Merriam. 

7. A Collection of Mammalian Remains from Tertiary Beds on the Mohave Desert, 

by John C. Merriam. 

Nos. 6 and 7 in one cover 10c 

8. The Stratigraphic and Faunal Relations of the Martinez Formation to the Chico 

and Tejon North of Mount Diablo, by Roy E. Dickerson 5c 

9. Neocolemanite, a Variety of Colemanite, and Howlite from Lang, Los Angeles 

County, California, by Arthur S. Eakle .'. 10c 

10. A New Antelope from the Pleistocene of Rancho La Brea, by Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part II. — Vertebrate Faunas 1.00 

12. A Series of Eagle Tarsi from the Pleistocene of Rancho La Brea, by Loye Holmes 

Miller _ 10c 

13. Notes on the Relationships of the Marine Saurian Fauna Described from the Triassic 

of Spitzbergen by Wiman, by John C. Merriam. 

14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13 and 14 in one cover 15o 

15. Notes on the Later Cenozoic History of the Mohave Desert Region in Southeastern 

California, by Charles Laurence Baker 50c 

16. Avifauna of the Pleistocene Cave Deposits of California, by Loye Holmes Miller .... 15c 

17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5c 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25c 

VOLUME 7. 

1. The Minerals of Tonopah, Nevada, by Arthur S. Eakle 25c 

2. Pseudostratification in Santa Barbara County, California, by George Davis Louder- 

back 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Rancho La Brea, by John C. 

Merriam 5c 

4. The Neocene Section at Kirker Pass on the North Side of Mount Diablo, by Bruce 

L. Clark 15c 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60e 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 17, pp. 287-292, 3 text figures Issued May 26, 1917 



AN EXTINCT TOAD FROM RANCHO LA BRKAr--: — : 

^ sonian 



CHARLES LEWIS CAMP 



nsti fl 



* JUN 7-1917 * 



INTRODUCTION 

The only amphibian remains so far discovered in the asphaliSte 
posits of Rancho La Brea are those of toads. This material includes, 
besides remains of the species now inhabiting the region (Bufo boreas 
halophilus), some limb-bones, vertebrae and part of a skull of an 
undescribed species of toad now extinct. But few fossil salientians 
have yet come to light, and as the fragile nature of their bones makes 
it improbable that very many ever will be found, unusual value at- 
taches to the present collection. The finding in the same Pleistocene 
deposits of numbers of beetles of a kind often fed upon by toads is 
significant ; and the discovery of bones of toads in the Pleistocene in 
as great numbers as in the Recent localities would seem to mean that 
toads were then as abundant in the region as they are today. 

The extinct species here described seems closely related to the 
Recent Bufo boreas, a species ranging along the Pacific Coast from 
southeastern Alaska to San Diego, California. There is unfortunately 
some question as to the exact locality of occurrence of the type skull 
of the fossil toad, and hence as to whether it is really a Pleistocene 
form ; but a parasphenoid from Pleistocene locality 2051 corresponds 
exactly with the type of the new species, and differs, as does the type, 
from the single parasphenoid from Recent locality 2052, and from 
B. boreas. Measurements of the parasphenoid from locality 2052, in 
addition to other skeletal measurements (see table II), seem to show 
that the toad from that locality resembles Bufo boreas more closely 
than the extinct form. 

BUFO NESTOR, n. sp. 
Type specimen, a portion of a skull, No. 22468, Univ. Calif. Coll. Vert. 
Palae., consisting of all the anterior cranial, otic, and occipital elements intact 
except for slight damage to the left frontoparietal. Locality 2051, Rancho 
La Brea, Los Angeles County, California. 



288 "University of California Publications in Geology [Vol. 10 



Fronto-parietals flat, not fused in midline, scarcely concave; 
dorsal surfaces considerably roughened ; sides nearly parallel and 
projecting downward slightly around the cranium. Sphenethmoid 
relatively large, deeply notched posteriorly, nearly in contact with 
prootics behind and involving cranium in a more complete ossifi- 
cation than in Recent toads of related species. Short posterior arm 
of parasphenoid, pointed ; anterior arm below cranium wider than in 
recent Bufo boreas; lateral wings below exoccipitals relatively and 
absolutely wider than in other species of the group ; a strong trans- 




3 

Figs. 1-3. Bufo nestor, n. sp. Skull, No. 22468, X 2. Fig. 1, dorsal view; 
fig. 2, ventral view; fig. 3, posterior view. Kancho La Brea Beds, California. 



verse ridge running medially through the lateral wings ; a roughened 
triangular elevation below intersection of wings and shaft ; outer an- 
terior borders of lateral wing not upturned in contact with pedicel 
of pterygoid. Prootics extensively ossified, longer in proportion to 
width than in Recent western toads. Squamosals small, triangular, 
flat and roughened above ; lying in the plane of the fronto-parietals 
and extending out above the prootics about half the length of the 
latter. Foramen magnum slightly wider than high; condyles meeting 
below ; extending about half way up sides of foramen and overlapping 
edges of latter inside about 0.4 millimeter. ' ' Condyloid ' ' foramen 
relatively and absolutely greater in diameter than in skulls at hand of 
Bufo boreas boreas and B. b. halophilus. 



1917 1 Camp: An Extinct Toad from Rancho La Brea 



289 



North American toads (Bufo) can be placed in three divisions: 
the americanus-lentiginosus-cognatus group with prominent angular 
head crests ; the debilis-punctatus-alvarius section with crests low and 
curved around the orbits and with broad fronto-parietals ; and the 
boreas-canorus group with no cranial crests (except in old adults) and 
with narrow fronto-parietals. It is to the latter division that the 
present species seems to belong. Bufo -nestor differs from existing 
Pacific Coast toads, of the forms related to B. boreas, in its wider, 
flatter and more roughened fronto-parietals; longer and wider sphen- 
ethmoid; stouter and posteriorly pointed parasphenoid ; flatter squa- 
mosals; mere slender prootics; larger and more completely protected 
brain-case. 

Other material, consisting of toad bones, doubtless of the above 
described species, from locality 2051, Rancho La Brea, is as follows: 
Fourteen vertebrae; 2 third, 1 fifth, and 4 ninth (sacral) ; one pelvis; 
one ilium ; eleven femora ; twenty-four tibio-fibulae ; fourteen humeri ; 
five radio-ulnae ; two complete and one fragmentary calcaneo-astragali ; 
and one parasphenoid. In addition to the above, there is toad material, 
from locality 2052, consisting of seven vertebrae: 1 third, 2 fourth, 
1 seventh, and 2 ninth (sacral) ; one ilium; twenty-one femora; thirty 
tibio-fibulae ; twenty-two humeri ; six radio-ulnae ; two complete and 
two fragmentary calcaneo-astragali; and one parasphenoid. 

The parasphenoid from locality 2051 agrees with the type in ratio 
of wing width to total length and in the pointed character of its 
posterior tip. It differs in the above characters from the parasphenoid 
from locality 2052 and from B. b. boreas and halophilus. 

Femora from localities 2051 and 2052 and of existing bo-re us are 
almost indistinguishable. The largest are only about two-thirds the 
length of a frog femur of medium size (Rana draytonii) , and all bear 
larger epiphyses than do corresponding bones of a specimen of spade- 
foot (Scaphiopus h. kammondii) at hand. The sigmoid curvature is 
more pronounced than in Bufo woodhousii. The smallest femur, from 
locality 2052, is much shorter than in Hyla arenicolor, but is thicker 
through the shaft. The largest specimens are longer than in any 
B. b. halophilus at hand and approach B. alvarius, but differ from 
that species in the more flattened character of the median ridge. A 
femur at hand of B. b. boreas from Vancouver Island is longer than 
any specimen from Rancho La Brea. 

Seventeen humeri from locality 2052 do not differ greatly except 
in size from existing B. b. halophilus. The longest is one-fourth 



290 University of California Publications in Geology [Vol. 10 



larger than the largest obtainable specimens of the existing forms and 
one-fifth longer than in the gigantic B. alvarius, which, however, is a 
short-armed species. These toad humeri differ from existing Rana in 
the greater expansion of the proximal ends, less degree of separation 
and lack of furrow ventrally (or posteriorly) between the middle 
rounded part and inner or post-axial condylar ridge of the distal 
end. Five of these seventeen humeri exhibit the cresta medialis of 
the male ; the others, including the four largest, are probably from 
females. Five humeri, from locality 2051, do not differ materially 
from those of 2052, and existing species, except that they do not attain 
such a great size as those from locality 2052. Two show only the 
cresta medialis. 

Radio-ulnae from the two Rancho La Brea localities show no 
perceptible differences in comparisons with specimens of B. b. boreas 
and B. b. halophilus. 

Twenty tibio-fibulae from locality 2052 are very similar to speci- 
mens of B. b. halophilus at hand. They are not so strongly curved 
or so large as in B. alvarius, not so small as in B. punctalus, differ 
from B. woodhousii in the plate-like character of the ventral part of 
the proximal epiphysis, differ from Rana in the greater ratio of length 
to breadth, and from SeapJiiopus in greater thickness. 

Seventeen tibio-fibulae, from locality 2051, are almost indistin- 
guishable from those occurring at locality 2052. 

Portions of two ossa innominata from 2051 resemble examples 
of B. b. boreas and halophilus in all characters but height of the 
ilium at its widest part. The Rancho La Brea specimens, perhaps 
referable to B. nest or, exhibit a higher, heavier ridge on this bone 
(which approaches the condition found in some of the Ranidae), fur- 
nishing better attachment for the powerful extensor, leaping muscles 
in the hind legs. 

Two sacral vertebrae from locality 2052 are procoelous and similar 
to B. b. halophilus and boreas, one is as large as in a specimen of B. 
alvarius, another smaller than in the largest B. b. halejphilus at hand. 
Tbe diapophyses are in each case strongly dilated. The angle the 
anterior edges of the diapophyses would make with one another when 
joined is less than 180 degrees. A sacrum from locality 2051 is small 
and seems relatively thicker and narrower than the corresponding 
bone in B. b. halophilus. 

The calcaneo-astragalus from locality 2051 seems to bear no dis- 
tinctive peculiarities. 



1917] 



Camp: An Extinct Toad from Bancho La Brea 291 



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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 18, pp. 293-326, 2 text figs., pis. 14-20 Issued November 8, 1917 



FAUNA OF THE SANTA MARGARITA BEDS IN 
THE NORTH COALINGA REGION 
OF CALIFORNIA 




UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



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Cited as Univ. Calif. Publ. Bull. Dept. Geol. 

Volume 1, 1893-1896, 435 pp., with 18 plates, price i. „ $3 50 

Volume 2, 1896-1902, 457 pp., with 17 plates and 1 map, price : $3.50 

Volume 3, 1902-1904, 482 pp., with 51 plates, price '.. $3.50 

Volume 4, 1905-1906, 478 pp : , with 51 plates, price $3.50 

Volume 5, 1906-1910, 458 pp., with 42 plates, price $3.50 

A list of titles in volumes 1 to 5 will be sent upon request. 

VOLUME 6. 

1. The Condor-like Vultures of Rancho La Brea, by Loye Holmes Miller 15« 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part I. — Geologic History 50c 

3. The Geology of the Sargent Oil Field, by William F. Jones 25c 

4. Additions to the Avifauna of the Pleistocene Deposits at Fossil Lake, Oregon, by 

Loye Holmes Miller ...... 10c 

5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe, by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of 'Rancho La Brea, by John C. 

Merriam. 

7. A Collection of Mammalian Remains from Tertiary Beds on the Mohave Desert, 

by John C. Merriam. 

Nos. 6 and 7 in one cover 10c 

8. The Stratigraphic and Faunal Relations of the Martinez Formation to the Chico 

and Tejon North of Mount Diablo, by Roy E. Dickerson 5c 

9. Neocolemanite. a Variety of Colemanite, and Howlite from Lang, Los Angeles 

County, California, by Arthur S. Eakle 10c 

10. A New Antelope from the Pleistocene of Rancho La Brea, by Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part If. — Vertebrate Faunas 100 

12. A Series of Eagle Tarsi from the Pleistocene of Rancho La Brea, by Loye Holmes 

Miller _. 10c 

13. Notes on the Relationships of the Marine Saurian Fauna Described from the Triassic 

of Spitzbergen by Wiman, by John C. Merriam. 

14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13 and 14 in one cover 15o 

15. Notes on the Later Cenozoic History of the Mohave Dese'rt Region in Southeastern 

California, by Charles Laurence Baker 50c 

16. Avifauna of the Pleistocene Cave Deposits of California, by Loye Holmes Miller .... 15c 

17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5c 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25c 



VOLUME 7. 

1. The Minerals of Tanopah, Nevada, by Arthur S. Eakle 25c 

2. Pseudostratification in Santa Barbara Cpunty, California, by George Davis Louder- 

back ! 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Rancho La Brea, by John C. 

Merriam 5 c 

4. The Neocene Section at Kirker Pass on the North Side of Mount Diablo, by Bruce 

L. Clark 15c 

5. Contributions to Avian Palaeontology- from the Pacific Coast of North America, by 

Loye Holmes Miller , 60e 



Vol. 10, No. 18, pp. 293-326, 2 text figs., pis. 14-20 Issued November 8, 1917 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 



FAUNA OF THE SANTA MARGARITA BEDS IN 
THE NORTH COALINGA REGION 
OF CALIFORNIA 

BY 

JORGEN O. NOMLAND 



CONTENTS 

PAGE 

Introduction 294 

Previous palaeontologic and geologic work 294 

Relation to other formations 296 

Lithologic section of the Santa Margarita northeast of Coalinga 298 

Fauna of the Santa Margarita northeast of Coalinga 299 

Other Santa Margarita localities compared 302 

Tejon Hills 302 

San Luis Quadrangle 302 

Salinas Valley 304 

Description of species 305 

Amiantis communis, n. sp 305 

Chione semiplicatus, n. sp 305 

Ostrea titan corrugata, n. var 306 

Pecten crassicardo biformatus, n. var 307 

Periploma clarki, n. sp 307 

Pinna bicuneata, n. sp 308 

Septifer margaritana, n. sp 308 

Acanthina (Monoeeras) noma, n. sp 309 

Fusinus fabulator, n. sp 309 

Purpura nanna, n. sp 310 

Teguia thea, n. sp 310 

Tegula varistriata, n. sp 311 

Trophon perelegans, n. sp 311 

Turritella freya, n. sp 312 

Turritella margaritana, n. sp 312 



294 University of California Publications in Geology [Vol. 10 



Introduction 

Since the first description of the Santa Margarita in the San 
Luis quadrangle by Dr. H. W. Fairbanks, the question of age of 
this formation has from time to time attracted much attention. 
Especially important has been the relation of the Santa Margarita to 
the upper Miocene and Pliocene formations in the vicinity of San 
Francisco Bay. The Santa Margarita was considered by Fairbanks 
a division of the San Pablo, while a number of other geologists have 
thought it older than that group. The preservation of the fossils of 
the Santa Margarita at the type locality is very poor. Few attempts 
have been made to list a typical Santa Margarita fauna, and correla- 
tion with other localities has been uncertain or frequently impossible. 
A study of the Santa Margarita fauna has therefore become highly 
important for correlation purposes. 

The present paper is a study of a fauna collected from beds in 
the north Coalinga region which have been correlated with the Santa 
Margarita. The palaeontologic studies apparently indicate that these 
beds represent the upper part of the San Pablo group. The faunas 
also indicate that they represent at least in part the same horizon as 
the Santa Margarita at the type locality. 

Most of the material studied from the Coalinga region was col- 
lected by Dr. B. L. Clark during his research on the fauna of the 
San Pablo group. The writer is much indebted to Dr. Clark for the 
use of his field notes on the geology and for numerous valuable sug- 
gestions, especially in regard to correlation with the San Pablo fauna. 
Dr. R. E. Dickerson kindly permitted the writer the use of material 
in the collections of the California Academy of Sciences, San Fran- 
cisco. 

Previous Palaeontologic and Geologic Work 

The first published account of palaeontologic and geologic investi- 
gation in the region north of Coalinga was included in a paper pub- 
lished in 1905 by F. M. Anderson. 1 In this publication the Santa 
Margarita was grouped with what he called the Coalinga Beds. These 
beds comprised what was later mapped as Vaqueros, Santa Margarita, 
and Jacalitos formations by members of the United States Geological 
Survey. A brief general description of the geology with faunal lists 



i Anderson, F. M., A stratigraphic study in the Mount Diablo Eange of 
California, Proe. Calif. Aead. Sei., ser. 3, vol. 2, no. 1, 1905. 



1917] Nomland: Fauna of the Santa Margarita Beds 295 



was given. The age of the beds corresponding to the " Jacalitos" was 
regarded as uppermost Miocene. 

In 1908 Anderson 2 published another paper including a descrip- 
tion of the same region. The term Coalinga Beds was then modified 
so as to comprise a part of the "Jacalitos" and the Santa Margarita 
above the lithologic member called the Big Blue. It was suggested 
that the Coalinga Beds might be the equivalent of the San Pablo in 
the northern part of the Mount Diablo Range. 

In the preliminary report on the Coalinga district by Ralph 
Arnold and Robert Anderson 3 in 1908, the Coalinga Beds as defined 
by F. M. Anderson were divided into Vaqueros, Santa Margarita, 
and Jacalitos formations. The name Santa Margarita was used be- 
cause of the similarity of the fossils to those occurring in that for- 
mation in the San Luis quadrangle in San Luis Obispo County. 
This formation was believed to be of upper middle Miocene age. The 
Big Blue was tentatively included with the Santa Margarita. 

In a bulletin by Ralph Arnold 4 on the palaeontology of the 
Coalinga district, a short list of species found in the Santa Mar- 
garita was given. The formation was believed to be at least in part 
older than the San Pablo. 

The latest report on the geology and oil resources of the Coalinga 
district by Arnold and Anderson 5 does not differ essentially from 
their earlier reports on this region. It includes a general discussion 
of both the palaeontology and geology. 

In the study of the palaeontology of the San Pablo group, B. L. 
Clark compared that fauna to the forms found in the Santa Mar- 
garita. It was shown that nearly one-half of the species found in 
the Santa Margarita also occur in the San Pablo. It was also stated 
that this formation was the equivalent of only the upper part, the 
Astrodapsis whitneyi zone, of the San Pablo. A historical summary 
of the literature dealing with the San Pablo-Santa Margarita was 
included. 

2 Anderson, F. M., A further study in the Diablo Bange of California, Proc. 
Calif. Acad. Sci., ser. 4, vol. 3, 1908. 

s Arnold, Ealph, and Anderson, Eobert, Preliminary report on the Coalinga 
Oil District, California, TJ. S. Geol. Surv., Bull. 357, 1908. 

* Arnold, Ealph, Palaeontology of the Coalinga district, Fresno and Kings 
counties, California, U. S. Geol. Surv. Bull. 396, 1909. 

s Arnold, Ealph, and Anderson, Eobert, Geology and oil resources of the 
Coalinga district, California, U. S. Geol. Surv. Bull.* 398, 1910. 

o Clark, B. L., Fauna of the San Pablo group of middle California, Univ. 
Calif. Bull. Dept. Geol., vol. 8, no. 22, 1915. 



296 University of California Publications in Geology [ VoL - 10 



The most recent report on the geology of this section of the 
state is on the region north of the Coalinga district by Robert Ander- 
son and Robert W. Pack. 7 The Big Blue is not included with the 
Santa Margarita, but is regarded as Vaqueros, this being based on 
fossils found in the region studied. The Santa Margarita is consid- 
ered older than the San Pablo. 

Relation to Other Formations 
The Santa Margarita formation of the San Pablo group as mapped 
in the Coalinga district is found in two areas. The lithology of these 
two regions is decidedly different. West and southwest of Coalinga 
the formation consists almost entirely of a light-colored diatomaceous 
shale. This shale in many characteristics is very similar to the 
Monterey Shale found in many parts of the Salinas Valley. At 
some localities west of Coalinga a thin basal sandstone is found con- 




Horizontal Distance represented about t Mttett 



Fig. 1. Generalized section across formations on east side of Diablo Range, 
northeast of Coalinga. Kck, Cretaceous; Ttj, Tejon (Eocene); Tel, Oligocene; 
Tt, "Temblor" (Miocene); Tsm, Santa Margarita (Miocene); Te, Etciiegoin 
(Pliocene) ; Tpr, Tulare (Pliocene) ; Qual, Pleistocene and Recent alluvium. 
(After Ruckman.) 

formably below the shale. From this member a small fauna has been 
obtained, which is the chief evidence favoring inclusion of this sand- 
stone and the shale above with the Santa Margarita. The shale west 
and southwest of Coalinga rests with large discordance in dip on the 
Vaqueros and is overlain unconformably by the Etchegoin. In the 
other area which is found north and northeast of Coalinga, the Santa 
Margarita is lithologically quite different from the diatomaceous 
shale. The formation here consists entirely of soft yellowish sand- 
stone which in many localities is highly fossiliferous. It is the fauna 
obtained from this area of Santa Margarita which will be described 
in the present paper. 

As shown by the mapping of the region north of Coalinga by 



7 Anderson, Robert, and Pack, Robert W., Geology and oil resources of the 
west border of the San Joaquin Valley north of Coalinga, California, U. S. Geol. 
Surv. Bull. 603, 1915. 



1917] Nomland: Fauna of the Santa Margarita Beds 297 



Arnold and Anderson,* and by Anderson and Pack, the Santa Mar- 
garita sandstone is continuous as a thin series of beds flanking the 
eastern slopes of the Diablo Range from near the town of Oilfields 
to a short distance north of Arroyo Honda. The formation is thus 
exposed for a length of somewhat more than twenty miles, being 
apparently overlapped in both the northern and southern ends by 
the younger Etchegoin. Another small exposure of the same forma- 
tion composed of fossiliferous sandstone is also found a few miles 
northwest of Coalinga. 

Considered as a whole, the Santa Margarita is decidedly distinct 
from the adjoining formations. At some localities, due to the simi- 
larity of lithology of the Santa Margarita near the base of the 
underlying lithologic member called the Big Blue, the line of con- 
tact is traced with difficulty. The Big Blue was therefore tentatively 
mapped with the Santa Margarita by Arnold and Anderson. The 
more recent work of Anderson and Pack 10 in the area north of the 
Coalinga district has shown that the Big Blue belongs with the 
Vaqueros and that it is unconformably related to the Santa Mar- 
garita. The Big Blue consists largely of deposits of serpentine detri- 
tus in part at least of land-laid origin. In the Coalinga district it is 
highly colored and is barren of marine invertebrate fossils. In the 
area north of the Coalinga district, however, Anderson and Pack 
report the finding of marine fossils in this member. 

The Santa Margarita is similarly decidedly distinct from the 
overlying Etchegoin. As already stated by the writer elsewhere, 11 
there appear to be good reasons for believing that the contact between 
the Santa Margarita and the Etchegoin is about two hundred feet 
stratigraphically lower than the line mapped by Arnold and Ander- 
son. The beds containing fossil remains of the Pliocene horse Neo- 
hipparion inolle Merriam would thus be included with the Etchegoin 
instead of the Santa Margarita. This will therefore be used as the 
base of the Etchegoin in the present paper. As thus defined, the 
beds lying immediately above the Santa Margarita have a number 
of characteristics indicative of terrestrial deposits. These beds are 

s Arnold, Ralph, and Anderson, Robert, Geology and oil resources of the 
Coalinga district, etc. 

9 Anderson, Robert, and Pack, Robert W., Geology and oil resources of the 
west border of the San Joaquin Valley, etc. 

10 Op. cit., p. 92. 

11 Nomland, J. O., Relation of the invertebrate to the vertebrate faunal zones 
of the Jacalitos and Etchegoin formations in the north Coalinga region, Califor- 
nia, Univ. Calif. Publ., Bull. Dept. Geol., vol. 9, no. 6, 1916. 



298 University of California Publications in Geology [Vol- 10 



highly colored, contain a large amount of silicified wood, leaves, and, 
as stated above, remains of land mammals. 

As will be shown by a study of the accompanying list of species, 
faunally the Santa Margarita differs markedly from both the 
Vaqueros below and the Etchegoin above. Only a few of the species 
are found in the adjoining formations. The nearest correlative of 
the Santa Margarita appears to be the upper part of the San Pablo 
group 12 as developed in the northern part of the Diablo Range. 

Lithologic Section of the Santa Margarita Northeast of 

Coaling a 

The sandstone member of the Santa Margarita as exposed in 
the area northeast of Coalinga was probably deposited, unlike the 
adjoining portions of the Vaqueros and Etchegoin, entirely under 
marine conditions. The following tabulated section indicates in a 
general way the lithologic character of the formation. It is to be 




Pig. 2. Detailed section across the Santa Margarita about ten miles north- 
east of Coalinga. Horizontal distance about 2500 feet. (After Clark and 
Euekman.) 

borne in mind, however, that the beds vary greatly within a short 
distance and that the section can be applied in detail to only a very 
limited area. 

Detailed Section op the Santa Margarita Ten Miles Northeast of Coalinga 



Etchegoin Feet 
Basal gravel with silicified wood and gypsum. Neohipparion molle 
found short distance above base 
Santa Margarita 

Gray thin-bedded sandstone with well-rounded pebbles of brown chert, 

quartzite, and quartz monzonite 2 

Buff to white, well-rounded, medium to coarse-grained sand 18 

Hard, coarse, quartzose sand with pebbles of quartz monzonite, andesite, 

and rhyolite; cement calcareous 13 

White to bluish-white, incoherent sand consisting chiefly of well-rounded 

quartz grains 50 

Fossiliferous grayish-brown sandstone with well-rounded grains of 

quartz and feldspar 25 



12 Clark, B. L., Fauna of the San Pablo group of middle California, Univ. 
Calif. Publ., Bull. Dept. Geo!., vol. 8, no. 22, 1915. 



1917] Nomland: Fauna of the Santa Margarita Beds 299 

Feet 

Hard grayish-brown sandstone; grains moderately well-rounded with 

pebbles of volcanic rocks 13 

Barnacle reef, with arkose sand and large number of specimens of 

Balanus 1 

Coarse, light-gray, pebbly sand with calcareous cement; pebbles sub- 
angular, chiefly andesite, quartz, and feldspar ; fauna includes Astro- 

dapsis amoldi, Ostrea vespertina 30 

Incoherent fossiliferous sand with large number of well-preserved speci- 
mens of Mytilus Tcewi 38 

Bed of Ostrea titan in ashy sand 1 

Fine ashy sand 25 

Tuffaeeous sand with Ostrea titan 1 

Fine ashy sand with grains of quartz and feldspar 19 

Ostrea titan in tuffaeeous sand 1 

A very persistent bed of bluish-gray water-laid volcanic ash. Unaltered 
feldspar, hornblende, and quartz ; also volcanic type of biotite. All 

grains angular and broken 25 

Unconsolidated gray sand consisting essentially of quartz, feldspar and 

biotite 19 

Eeef with numerous specimens of Ostrea titan 3 

Very fine-grained arkose sand interstratified with layers of rhyolitic ash ; 

has large number of crab borings 25 

Bed consisting largely of shells of Ostrea titan 3 

Fine gray sand with minute rounded grains of serpentine 57 

Highly fossiliferous conglomerate composed mostly of shells of Ostrea 

titan, Tamiosoma gregaria, Pecten estrellanus 2 1 /2 

Incoherent buff to brown arkose sand with minute fragments of ser- 
pentine 30 

Basal coarse to medium-grained sand with well-rounded pebbles of 
serpentine ; matrix chiefly orthoclase, and quartz ; cemented by 
calcium carbonate 25 



Total thickness 426% 

Vaqueros 

Big Blue serpentinous member. 

Fauna of the Santa Margarita Northeast of Coalinga 
In the report on the palaeontology of the Coalinga district by 
Ralph Arnold, 13 a brief Santa Margarita faunal list was included. 
This list comprised the following species : 

Fossils from the Santa Margarita, Listed by Arnold 

Astrodapsis whitneyi Eemond Pecten crassicardo Conrad 

Cliione eonradiana Anderson Pecten estrellanus Conrad 

Cryptomya ovalis(?) Conrad Solen sicarius Gould 

Dosinia ponderosa Gray Zirphaea dentata Gabb 

Hinnites giganteus Gray Trophon carisaensis Anderson 

Macoma nasuta Conrad Tamiosoma gregaria Conrad 
Ostrea titan Conrad 



is Arnold, Ralph, Palaeontology of the Coalinga district, Fresno and Kings 
counties, etc. 



300 University of California Publications in Geology [ v °l. 10 



The Santa Margarita formation northeast of Coalinga is in many 
localities exceedingly fossiliferous, although the number of species is 
usually not great. The species of most common occurrence are Ostrea 
titan Conrad, Ostrea titan corrugata, n. var., Pecten estrellanus Con- 
rad, Pecten crassicardo Conrad, and Tamiosoma gregaria Conrad. 
A large number of the forms indicate that the Santa Margarita is 
closely related to the upper part of the San Pablo to the north. 
Among others may be mentioned the following species : Dosinia 
arnoldi Clark, Dosinia merriami occidentalis Clark, Macoma diablo- 
ensis Clark, Mya dickersoni Clark, Pinna alamedensis Yates, Pinna 
bicuneata, n. sp., Canccllaria pabloensis Clark, Natica diabloensis 
Clark, Trophon carisacnsis Anderson. The species obtained from the 
Santa Margarita north of Coalinga in the collections studied by the 
writer include the following : 

List of Species from the Santa Margarita North of Coalinga 



Echinodermata *s a 

>ir> K 

Astrodapsis calif ornicus Kew (MS) 

Astrodapsis eoalingaensis Kew (MS) 

Astrodapsis eoalingaensis grandis Kew (MS) 

Astrodapsis scutelliformis Kew (MS) 

Bryozoa 

Several species 

Peleeypoda 

Amiantis communis, n. sp 

Amiantis, sp. (large) 

Cardium quadrigenarium Conrad x x 

Chione semiplicatus, n. sp 

Dosinia arnoldi Clark x 

Dosinia merriami occidentalis Clark x 

Glycimeris, cf. coalingensis Arnold 

Macoma diabloensis Clark 

Macoma indentata Carpenter 

Macoma nasuta (Conrad) x x 

Macoma secta (Conrad) x x 

Metis alta (Conrad) x x 

Mya dickersoni Clark x 

Mya (Platydon) cancellatus Conrad x 

Mya ( Cryptomya ) ovalis Conrad x 

Mytilus kewi Nomland 

Ostrea titan Conrad ? x 

Ostrea titan corrugata, n. var 

Ostrea vespertina Conrad " x 

Panope generosum Gould x x 

Pecten crassicardo Conrad x x 

Pecten estrellanus Conrad x x 

Pecten (Hinnites) giganteus (Gray) x 



1917] Nomland: Fauna of the Santa Margarita Beds 



301 



3 J= 

? S 

« <u 

> Ph 

Pecten hastatus Sowevby 

Pecten raymondi Clark 

Periploma elarki, n. sp 

Phaeoides annulatus (Reeve) 

Phaeoides nuttalli (Conrad) 

Phaeoides sanctaecrusis Arnold x 

Pinna alamedensis Yates x 

Pinna bicuneata, n. sp 

Pitaria stalderi Clark 

Psammobia, cf. edentula (Gabb) 

Saxidomus nuttalli Conrad 

Septifer margaritana, n. sp 

Siliqua lucida (Conrad) 

Solen perrini Clark 

Spisula, cf. catilliformis (Conrad) 

Tellina, sp 

Venus, cf . martini Clark 

Venus pertenuis Gabb 

Zirphaea, aff. crispata (Linne) 

Gastropoda 

Aeanthina (Monoceras) noma, n. sp 

Calyptraea, cf. filosa (Gabb) 

Calyptraea martini Clark 

Cancellaria pabloensis Clark 

Chrysodomus, cf. pabloensis Clark 

Crepidula princeps Conrad 

Ficus, ef . nodiferous Gabb 

Liomesus, sp 

Nassa, sp 

Natica diabloensis Clark 

Natica reeluziana Petit 

Natica reeluziana andersoni Clark (MS) 

Purpura nanna, n. sp 

Sinum scopulosum Conrad 

Siphonalia danvillensis Clark 

Tegula thea, n. sp 

Tegula varistriata, n. sp 

Trophon carisaensis Anderson 

Trophon perelegans, n. sp 

Turritella freya, n. sp 

Turritella, sp. (large) 

Cirripedia 

Balanus concavus Bronn X 

Tamiosoma gregaria Conrad 

Pisces 

Fish vertebrae 

Shark teeth 



X X 
X 



Number of species in common with the Santa 
Margarita 15 



29 



18 16 



302 University of California Publications in Geology [Vol. 10 



Other Santa Margarita Localities Compared 
TEJON HILLS 

In the Tejon Hills at the south end of the San Joaquin Valley, a 
fauna has been collected 14 which includes several typical Santa Mar- 
garita species. The fossils occur in coarse, white, arkose sand with 
lenses of clay and gravel. The pebbles consist essentially of rhyolite. 
The fossiliferous marine member is about 50-100 feet thick. Above 
this member is a formation consisting of reddish land-laid beds, the 
Chanac formation, in which remains of land mammals are found. A 
lower Pliocene horse, Protohippus tejonensis, has been described from 
the land-laid beds by Professor Merriam. 15 It resembles very closely 
a form listed by Arnold and Anderson 10 and by the writer 17 from near 
the base of the "Jacalitos" formation in the Coalinga region. The 
marine invertebrate fauna collected in the Santa Margarita of the 
Tejon Hills consists of the following species : 

Santa Margarita Fauna from Tejon Hills 

Pelecypoda Saxidomus nuttalli Conrad 

Dosinia ef. arnoldi Clark Siliqua, cf. lueida (Conrad) 

Metis alta (Conrad) Solen, sp. 

Ostrea titan Conrad Teredo, sp. 

Ostrea, of. vespcrtina Conrad Venus pertenuis Gabb 

Pecten crassicardo Conrad Gastropoda 

Peeten crassicardo biformatus, Bulla, sp. 

n. var. Calyptraea, sp. 

Pecten hastatus Sowerby Conus, sp. 

Pecten raymondi Clark Fusinus tabulator, n. sp. 

Phacoides richthofeni (Gabb) Nassa pabloensis Clark 

Phacoides sanctaecrusis Arnold Natica, sp. 

Pinna alamedensis Yates Pisces 

Pitaria stalderi Clark Shark teeth 

SAN LUIS QUADRANGLE 
A Santa Margarita fauna has been collected 18 from a sandstone 
member at the base of what has been mapped as Monterey shale by 
Fairbanks 19 in the San Luis Quadrangle. The sandstone is of a 



14 Tejon Ranch, about twenty miles southeast of Bakersfield, Caliente quad- 
rangle; on west side of last large tributary of Tejon Creek, which cuts the Tejon 
Hills near north end, approximately western boundary of NW Vi sec. 13, T. 32 S, 
R. 29 E, M. D. B. & M. Collected by Dr. B. L. Clark. 

15 Merriam, J. C, New horses from the Miocene and Pliocene of California, 
Univ. Calif. PubL, Bull. Dept. Geol., vol. 9, no. 4, p. 52, 1915. Also: Merriam, 
J. C, Mammalian remains from the Chanac formation of the Tejon Hills, Cali- 
fornia, Univ. Calif. Publ., Bull. Dept. Geol., vol. 10, no. 8, pp. 111-127, 1916. 

is Arnold, Ralph, and Anderson, Robert, Geology and oil resources of the 
Coalinga district, etc. 

it Nomland, J. O., Relation of the invertebrate to the vertebrate faunal zones 
of the Jacalitos and Etchegoin formations in the north Coalinga region, Califor- 
nia, etc. 

is Approximately northern boundary of sec. 18, T. 29 S, R. 11 E., M. D. B. & 
M. Collected by B. L. Clark. 

is Fairbanks, H. W., U. S. Geol. Surv., San Luis Folio, no. 101, 1904. 



1917] Nomland: Fauna of the Santa Margarita Beds 



303 



yellowish-brown color and has a thickness of about fifty feet. The 
basal conglomerate, containing numerous specimens of Ostrea titan, 
overlies serpentine of Mesozoic age in which are numerous Pholas (?) 
borings. A light-colored cherty shale rests conformably on the sand- 
stone. The invertebrate fauna consists of the following identifiable 
forms : 

Santa Margarita Fauna at Base of ' ' Monterey ' ' Shale 
Astrodapsis tumidus Eemond Pliaeoides annulatus (Keeve) 

Mytilus, sp. Pholas('?), sp. 

Ostrea titan Conrad Psammobia, sp. 

Pecten crassicardo Conrad Spisula, sp. 

Pecten crassicardo biformatus, Tamiosoma gregaria Conrad 

n. var. 

In the northeastern part of the San Luis quadrangle a fauna has 
been collected 20 in a coarse white calcareous sandstone. The preser- 
vation of the fossils is very poor and usually only molds and casts 
are present. On comparison of this fauna with that of the upper 
San Pablo, a close relationship is apparent. The fauna from this 
locality, the type section of the Santa Margarita formation, was 
identified as follows : 

Santa Margarita Fauna from the Type Section 

Eehinodermata Pholas, sp. 

Astrodapsis margaritanns Psammobia, sp. 

Kew (MS) Saxidomus nuttalli Conrad 

Astrodapsis tumidus Eemond Schizothaerus nuttalli Conrad 

Astrodapsis whitneyi Eemond Solen, sp. 

Bryozoa Tellina, sp. 

Two species Tivela, sp. 

Pelecypoda Gastropoda 

Area trilineata Conrad Astralium raymondi Clark 

Cardium quadrigenarium Con- Bulla, sp. 

rad Calyptraea martini Clark 

Cardita, sp. Calyptraea, sp. 

Chione, sp. Chrysodomus, sp. 

Glycimeris, sp. Crepidula, sp. 

Maeoma, sp. Murex, sp. 

Metis alta (Oonrad) Nassa, sp. 

Mytilus, cf. coalingensis Natica, sp. 

Arnold Olivella, sp. 

Ostrea titan Conrad Trophon, sp. 

Ostrea, sp. (small) Turritella freya, n. sp. 

Paphia, sp. Turritella margaritana, n. sp. 

Panope generosum Gould Cirripedia 

Pecten estrellanus Conrad Tamiosoma gregaria Conrad 

Pecten raymondi Clark Pisces 

Phacoides nuttalli (Conrad) Shark teeth 



20 At several localities on Santa Margarita Creek and Trout Creek, near the 
town of Santa Margarita, San Luis quadrangle. Type section of the Santa 
Margarita formation. Collected by E. E. Dickerson and W. Gordon. 



304 University of California Publications in Geology [Vol. 10 



SALINAS VALLEY 



The Santa Margarita is extensively exposed along the Nacimiento 
and San Antonio Rivers several miles west of San Miguel, San Luis 
Obispo County. The formation here consists of a grayish-white sand- 
stone several hundred feet in thickness, resting on banded siliceous 
Monterey shale. The unconformity between these formations in this 
vicinity is very marked, so that while the Monterey has been intensely 
folded and faulted, the overlying Santa Margarita usually has rela- 
tively gentle dips. The lithology and included fauna indicate that 
this formation was here deposited near the ocean shore. Prom the 
distribution of these sandstones it is evident that the Santa Lucia 
Mountains were at this time above water and that the sediments must 
have been derived from this range. Also it is evident that following 
the folding of the Monterey, prior to or during Lower San Pablo time, 
this range was subjected to extensive erosion and probable mountain- 
making movements, while during the Upper San Pablo, or Santa Mar- 
garita time, an extensive transgression occurred. From the sand- 
stones near the base on the north side of the Nacimiento River, about 
eight miles west of San Miguel, the following fauna was obtained : 



The Santa Margarita also has a large areal extent in the eastern 
part of Monterey County along tributaries entering the Salinas River 
from the east. Among these may be mentioned Cholame Creek, Vine- 
yard Creek and Indian Valley. This formation at some localities 
shows exposures estimated at 1200-2000 feet, consisting essentially of 
shale in many respects lithologically similar to the Monterey. On 
Vineyard Creek in the lower portion of the formation, are found 
highly fossiliferous beds of sandstone and conglomerate with a typical 
Santa Margarita fauna. Above the Santa Margarita in this region 



Santa Margarita Fauna from Nacimiento Eiver 



Bryozoa, sp. 
Brachiopod, sp. A. 
Astrodapsis antiselli Conrad 
Astrodapsis margaritanus Kew 



(Gray) 
Pecten raymondi Clark 
Pecten sancti-ludovici Anderson 



Ostrea, sp. (small) 
Pecten estrellanus Conrad 
Pecten (Hinnites) giganteus 



(MS) 
Calyptraea, sp. 
Crepidula, sp. 
Lima, sp. 

Metis alta (Conrad) 
Mytilus kewi Nomland 
Ostrea titan Conrad 
Ostrea titan corrugata, n. var. 



and Martin 
Pecten, sp. A. 

Sehizothaerus, cf. nuttalli Conrad 
Trophon perelegans, n. sp. 
Turritella, sp. 
Balanus coneavus Bronn 



1917] Nomland: Fauna of the Santa Margarita Beds 305 



are found sandstones and conglomerates of Lower Etchegoin age con- 
taining among other species several varieties of Astrodapsis arnoldi 
Pack. 

Description of Species 
AMIANTIS COMMUNIS, n. sp. 
Plate 14, figures 2a, 2b, 2c, 2d 
Type specimen, no. 11311, in Univ. Calif. Coll. Invert. Pal., from locality 
2276, on hill near SW corner of SE % of NE % sec. 10, T. 19 S, E. 15 E, 
M. D. B. & M. 

Shell large, rather thick, inequilateral, equivalve ; umbones promi- 
nent, incurved, a little more than one-third of length of shell from 
anterior extremity. Anterior dorsal margin short, concave ; posterior 
dorsal margin long, gently convex ; ventral margin evenly arcuate ; 
anterior end strongly curved ; posterior extremity angulated. Lunule 
large and deep; escutcheon rather wide, extending nearly to posterior 
end, more strongly depressed on right than on left valve. Surface 
ornamented by numerops lines corresponding to stages of growth. 
Left valve with three cardinals and a lateral ; anterior cardinal thin, 
close to middle cardinal. Right valve with bifid posterior cardinal. 
Nymph plates of both valves long and narrow. Dimensions : Height, 
75 mm. ; length, 82 mm. ; thickness, 41 mm. 

Pitaria diabloensis (Anderson) which also occurs in the Miocene 
of this region is somewhat similar in outline to this species, but may 
be distinguished from it by the long, narrow escutcheon, the smaller 
and shorter cardinal of the left valve, and the anterior and middle 
cardinals are nearer together. 

Occurrence. — At localities 2276, 2278, northeast of Coalinga, 
Santa Margarita. At the type locality this species occurs with Chione 
semiplicata, n. sp. ; Periploma clarki, n. sp. ; Septifer margaritana, 
n. sp ; Acanthina noma, n. sp. ; Tegirta thca, n. sp ; Tegula varistriata, 
n. sp. 

CHIONE SEMIPLICATA, n. sp. 
Plate 15, figures 2a, 21, 2c 
Type in Univ. Calif. Coll. Invert. Palae., a nearly perfect specimen of left 
valve, no. 11318, from locality 2283, in small gully near SE corner of NW % 
of NW % sec. 15, T. 19 S, R. 15 E, M. D. B. & M., about nine miles northeast of 
Coalinga. 

Shell subquadrangular to triagonal in outline; beaks prominent 
and strongly curved inwards, about one-fourth of length of shell 
from anterior end ; interior margins faintly crenulate ; anterior end 



306 University of California Publications in Geology [Vol. 10 



approximately a right angle ; flattened on sides of posterior portion 
of shell from beak to posterior dorsal margin. Anterior dorsal margin 
short and strongly concave ; anterior ventral margin convex, becom- 
ing nearly straight near anterior end. Posterior dorsal margin long, 
nearly straight near middle, with increasing convexity towards ends; 
posterior ventral margin regularly arcuate. Lunule large, strongly 
depressed ; escutcheon long, rather narrow. Surface of shell orna- 
mented on sides by prominent concentric growth lines and radiating 
ribs of medium width. Middle and posterior cardinal tooth of right 
valve bifid ; anterior cardinal small ; nymph plates long and heavy. 
Posterior cardinal heavy, bifid ; anterior cardinal long and rather 
narrow. Dimensions: Height, 71 mm.; length, 80 mm. 

Chione temblorensis Anderson resembles Chione semiplicata, n. sp. 
The latter, however, may be readily distinguished by not having the 
marked depression on the sides at the posterior end and has more 
anterior beaks. From Chione elsmerensis English it differs in having 
shorter and more concave anterior dorsal margin, more convex ventral 
margin and weaker hinge. 

Occurrence. — At localities 2276, 2283, in the Santa Margarita. 



OSTREA TITAN CORRUGATA, n. var. 
Plate 16, figure 1 ; plate 17, figure 1 
Type a well preserved specimen of lower valve, no. 11309, in Univ. Calif. Coll. 
Invert. Palae., from locality 2284, near middle of southern boundary of NE % 
sec. 10, T. 19 S, R. 15 E, M. D. B. & M., about fifty feet above base of formation. 

Shell large, very heavy, when full grown sub-ovate but in earlier 
stages of very irregular outline. Surface sculptured by well marked 
growth lines which at the edges are irregularly folded into prominent 
radiating ridges. Ligamental groove wide, triangular, extending 
nearly across anterior end of shell. Muscular impression large, 
rectangular, almost invisible in type. Dimensions of lower valve : 
length, 235 mm. ; width, 150 mm. ; height, 120 mm. 

Distinguishable from the typical Ostrea titan Conrad which is 
also found in the Santa Margarita formation by the prominent folds 
on surface and the greater convexity of lower valve. 

Occurrence. — At locality 2281, Santa Margarita, about ten miles 
northeast of Coalinga, Fresno County; northern end of Huasna Val- 
ley, San Luis Obispo County; Vineyard Creek anticline, Monterey 
County. 



1917] Nomland: Fauna of the Santa Margarita Beds 307 



PECTEN CRASSICARDO BIFORMATIS, n. var. 
Plate 18, figures 1, la, lb; plate 19, figure 4 
Type a well-preserved specimen of left valve, no. 11308, from locality 3029, 
near western boundary of sec 13, T. 32 S, R. 29 E, M. D. B. & M., Tejon Hills, 
Caliente Quadrangle, Kern County. 

Shell equilateral, equivalve, thin, rather compressed ; with more 
or less serrate, regularly convex, basal margins. Right valve with 
about fifteen high, squarish, rather narrow ribs; interspaces consider- 
ably wider than ribs, both being ornamented by numerous fine radiat- 
ing lines ; surface sculptured by fine, almost invisible, imbricate lines ; 
the larger specimens frequently show abrupt constrictions or undula- 
tions at later stages of growth. Anterior ear ornamented with incre- 
mental growth lines and about six radiating ridges ; posterior ear 
smaller but otherwise similar to anterior. Left valve with about 
fifteen-seventeen high squarish ribs. These are wider than the inter- 
spaces or than the ribs of the other valve, ornamented with fine 
incremental lines ; byssal notch well developed. Dimensions of type : 
Height, 92 mm. ; length, 114 mm. ; length of hinge line, about 65 mm. ; 
umbonal angle, 110 degrees. 

This species differs from the typical form in having higher and 
narrower ribs, especially in the left valve, and more compressed sides 
with abrupt constrictions. 

Occurrence. — Locality 3029, Tejon Hills, Santa Margarita forma- 
tion ; San Pablo group, Concord quadrangle, Contra Costa County ; 
Santa Margarita beds, San Luis quadrangle, San Luis Obispo County. 

PERIPLOMA CLARKI, n. sp. 
Plate 19, figure 6 

Type, no. 11320, in Univ. Calif. Coll. Invert. Palae., from locality 2278, near 
center of sec. 15, T. 19 S, R. 15 E, M. D. B. & M., about nine miles northeast 
of Coalinga. 

Shell of medium size, elliptical, thin, with right valve much deeper ; 
left valve flattened. Umbones small, about three-fourths of length 
of shell from anterior extremity. Shell rather strongly produced 
anteriorly, angulated at anterior extremity ; anterior dorsal margin 
gently convex ; anterior ventral margin with slight angle near middle. 
Posterior portion of shell short ; some specimens have depression 
extending from beak to posterior ventral margin, with distinctly 
biangulate end; posterior dorsal margin slightly convex; posterior 



308 University of California Publications in Geology [Vol. 10 



ventral margin gently convex to nearly straight. Dimensions : Height, 
32 mm. ; length, 41 mm. ; thickness, 14 mm. 

This species resembles in a general way Periploma argent aria 
Sowerby. In Periploma clarki, n. sp., the shell is, however, higher 
and thicker in proportion to its length, the anterior end is much 
shorter, the posterior end is biangulate, and the posterior dorsal 
margin straighter. 

Occurrence. — At localities 2276, 2278, 2279; Santa Margarita. 

Named in honor of Dr. B. L. Clark of the Department of Palaeon- 
tology at the University of California. 

PINNA BICUNEATA, n. sp. 
Plate 15, figures la, lb 
Type in Univ. Calif. Coll. Invert. Palae., no. 11307, from locality 2284, near 
middle of southern boundary of NE % sec. 10, T. 19 S, E. 15 E, M. D. B. & M., 
about fifty feet above base of Santa Margarita, ten miles northeast of Coalinga. 

Shell elongate-cuneate ; in cross-section thin, acutely elliptical. 
Hinge line long, nearly straight; ventral margin slightly concave 
near beaks ; posterior end evenly rounded. Sculptured by approx- 
imately ten distinct radiating ridges which appear to be absent on 
lower one-third of shell. 

Dimensions of type with broken posterior end : Length, 96 mm. ; 
width, 44 mm. ; thickness, 18 mm. ; umbonal angle, 35 degrees. 

This form may be distinguished from Pinna alameclensis Yates, 
which also occurs in the same beds, by its smaller size, long, straight 
hinge-line and ventral margin, less number of radiating ridges, and 
in being thinner in cross-section. 

Occurrence. — In the Santa Margarita, locality 2284, near Coalinga; 
in upper San Pablo group, locality 1245, Las Trampas Ridge, Concord 
quadrangle, Contra Costa County ; near Standard Oil Co. Powell 
well, eight miles northeast of Bradley, Monterey County, Lower 
Etchegoin ( ?). 

SEPTIFEB MABGABITANA, n. sp. 
Plate 19, figure 5 

Type in Univ. Calif. Coll. Invert. Palae., no. 11310, from locality 2276, on hill 
near SW corner of SE % of NE % sec. 10, T. 19 S, B. 15 E, M. D. B. & M. 

Shell long, cuneate, rather thick ; beaks pointed, terminal ; with 
well-developed umbonal ridge extending to posterior ventral margin. 
Anterior dorsal margin slightly concave ; posterior dorsal margin 
regularly convex ; posterior end evenly rounded ; ventral margin a 
little concave at middle but becoming convex about one-third of 



1917] Noml-and: Fauna of the Santa Margarita Beds 



309 



length of shell from anterior end. Surface ornamented by a large 
number of fine radiating ridges and well-developed growth lines. 
Dimensions : Length, 52 mm. ; height, 22 mm. 

This species is much larger than the Kecent Septifer bifurcatus 
Conrad, the radiating ridges are more numerous, and the umbonal 
ridge is more marked. 

Occurrence. — At locality 2276, Santa Margarita, about ten miles 
northeast of Coalinga. 

ACANTHINA (MONOCEEAS) NORNA, n. sp. 
Plate 19, figures 3a, 36 
Type specimen, no. 11314, in Univ. Calif. Coll. Invert. Palae., from locality 
2276, on hill near SW corner of SE % of NE % sec. 10, T. 19 S, R. 15 E, M. D. 
B. & M. 

Shell of medium size, fusiform, six or seven whorls, spire elevated, 
with distinctly appressed suture and a slight constriction on each 
whorl a short distance below. Body whorl slightly flattened on sides 
with rather acute angulation at shoulder; ornamented below angula- 
tion by about eleven well-developed spiral cords between each pair 
of which occurs a small spiral line ; at the shoulder a slight nodosity 
is evident. Whorls of spire with about five spiral ribs between each 
pair of which is a riblet ; with about twelve well-developed axial ribs 
which become smaller at lower part of whorls. Aperture narrow 
elliptical ; outer lip thickened, dentate ; inner lip incrusted, slightly 
flattened ; canal curved, of medium length. Dimensions : Height, 41 
mm. ; maximum diameter, 20 mm. 

Occurrence. — At locality 2276, about ten miles northeast of 
Coalinga, Fresno County ; Santa Margarita. At the type locality this 
species occurs with the following Santa Margarita forms : Amiantis 
communis, n. sp. ; Chione semiplicata, n. sp. ; Periploma clarki, n. sp. ; 
Septifer margaritana, n. sp. ; Tcejula thea, n. sp. ; Tegula varistriata, 
n. sp. 

FUSINUS FABULATOR, n. sp. 
Plate 20, figure 10 

Type decollete and broken specimen, no. 11319, in Univ. Calif. Coll. Invert. 
Palae., from locality 3029, near western boundary of sec. 13, T. 32 S, R. 29 E, 
M. D. B. & M., Tejon Hills, Caliente quadrangle, Kern County. Collected by 
R. C. Stoner. 

Shell of medium size, fusiform, elongate, about five or six whorls, 
with a little increased convexity at shoulder ; suture slightly appressed. 



310 University of California Publications in Geology [Vol. 10 



Whorls crossed by about twelve prominent rounded ridges which are 
highest at shoulder and become nearly obsolete at the upper and the 
lower part of the whorl. Spiral sculpture on body whorl consists of 
approximately twenty distinct ribs with very narrow interspaces ; 
whorls of spire with about eight spiral ribs. Aperture pyriform ; 
canal broken. Dimensions : Maximum diameter, 28 mm. ; height 
unknown. 

Occurrence. — In the Santa Margarita, at locality 3029. 

PURPURA NANNA, n. sp. 
Plate 19, figures la, lb 
Type specimen, no. 11315, in Univ. Calif. Coll. Invert. Palae., from locality 
2279, near center of SE % of NE % sec. 15, T. 19 S, E. 15 E, M. D. B. & M., 
about nine miles northeast of Coalmga. 

Shell muriciform, thick, medium in size ; with three prominent, 
thick, longitudinal varices on each whorl. Body whorl ornamented 
with six or seven well-developed spiral cords alternating with cords 
of less prominence ; in the interspaces between the two series may 
be seen on well-preserved specimens one or two threadlets ; at the 
shoulder between each pair of axial varices is a prominent node. 
Aperture acutely elliptical ; outer lip thick, dentate along inner edge ; 
inner lip with thin callus ; canal in type closed, curved. Dimensions : 
Maximum diameter, 34 mm. ; height of type, which has a broken 
spire, 51 mm. 

This species resembles somewhat closely Purpura foliata Martyn; 
but has a somewhat more elongated form, stronger nodes between the 
varices, a development of fine threadlets between the spiral cords, 
and the varix on the front side of body whorl projects forwards, thus 
not having the flattened appearance evident on a front view of Pur- 
pura foliata Martyn. 

Occurrence. — At locality 2279, in the upper part of the Santa 
Margarita. 

TEGULA THEA, n. sp. 
Plate 20, figures 6, 7a, 7b 

Type specimen, no. 11317, from locality 2275, near SW corner of NE y± of 
NE % sec. 33, T. 18 S,.R. 15 E, M. D. B. & M., eleven miles northeast of 
Coalinga. 

Shell conical ; apex acute ; suture slightly depressed ; whorls about 
five, with flattened sides and well-marked shoulder. Body whorl 
ornamented by three broad spiral ridges of which the one near the 



1917] Nomland: Fauna of the Santa Margarita Beds 311 



base is narrower ; between these are wide interspaces, the lower being 
of less width ; both ridges and interspaces covered by nine or ten 
spiral threads, of which the one at the shoulder and the two at the 
base are wider and more prominent; above the shoulder are about 
five equal spiral lines ; the oblique incremental lines crossing the 
spirals give the surface a slight nodose appearance. Base of body 
whorl convex, sculptured by about ten distinct concentric lines, which 
in general become finer away from the center. Aperture subcircular; 
outer lip rather thick ; on inner lip is small tubercle ; umbilicus open. 
Dimensions: Height, 16 mm.; maximum diametear, 22 mm. 

Occurrence.— At localities 2268, 2275, 2276, 2279, 2283; Santa 
Margarita. 

TEGULA VARISTEIATA, n. sp. 
Plate 20, figures 4a, 4b 
Type in Univ. Calif. Coll. Invert. Palae., no. 11316, from locality 2268, along 
side of canon, SW corner of NE % of NE % sec. 15, T. 19 S, E. 15 E, M. D. 
B. & M., about nine miles northeast of Coalinga, Fresno County. 

Shell conical, sides and upper part of whorls convex, about five 
whorls, with a slight shoulder on some specimens. Body whorl sculp- 
tured by about fifteen approximately equal spiral lines with narrower 
interspaces ; oblique incremental lines intersecting spirals give a 
nodose appearance. Base of body whorl convex ; ornamented by about 
eleven approximately equal concentric nodose lines. Aperture sub- 
ovate ; inner lip with small tooth or tubercle ; umbilicus open. Dimen- 
sions of type : Height, 20 mm. ; diameter, 21 mm. 

In some respects this species resembles closely Tegula thea, n. sp. 
It may be distinguished from that form by the nearly uniform con- 
vexity and the lack of the three prominent ridges on the sides of the 
whorls. 

Occurrence. — In the Santa Margarita at localities 2268, 2276, 
2282. 

TKOPHON PERELEGANS, n. sp. 
Plate 20, figures 1, 2, 3 
Type specimen, no. 11321, in Coll. Vert. Palae. of Calif. Acad. Sci., San 
Francisco; from near Graham oil well, western boundary sec. 2, T. 19 S, R. 15 E, 
M. D. B. & M., about eleven miles northeast of Coalinga, Fresno County. 

Shell of medium size ; spire rather high ; whorls about six ; suture 
indistinctly appressed. Whorls with slight angle on each whorl, a 
little below the suture, above which the surface is gently convex ; 
ornamented by about eleven thin axial varices which become spinose 



312 University of California Publications in Geology [Vol. 10 



at angulation. Body whorl with well-marked groove at about middle 
of distance between angulation and end of canal ; ornamented on the 
sides by about eight to ten distinct, subequal, spiral ridges which be- 
come almost obsolete immediately below the angulation ; axial varices 
extend across groove down about one-half of length of canal. Aper- 
ture ovate ; outer lip thin ; with long, rather wide, recurved canal. 
Dimensions : Maximum diameter, 26 mm. ; height unknown. 

This species is apparently closely related to Trophon coalingensis 
Arnold. It may readily be distinguished from that form, however, 
by having a higher spire, longer canal, and less number of axial 
varices. From such forms as Trophon stuarti Smith and Trophon 
gracilic Perry, it differs among other characteristics in having the 
deep groove at lower part of body whorl. 

Occurrence. — Rare in the upper Santa Margarita, northeast of 
Coalinga ; Nacimiento River eight miles west of San Miguel, San Luis 
Obispo County ; Vineyard Creek anticline, Monterey County. 

TURRITELLA FREYA, n. sp. 
Plate 19, figure 2 

Type an imperfect specimen, no. 11313, from locality 2283, near SW corner 
of NW % sec. 15, T. 19 S, R. 15 E, M. D. B. & M., Coalinga quadrangle. 

Shell tapering rapidly, number of whorls unknown ; with dis- 
tinct, slightly impressed suture. Whorls flat with a wide ridge near 
middle ; immediately above the suture are two prominent spiral 
cords with interspaces of about the same width ; between the middle 
ridge and suture above, a slight tendency to depression is noticeable ; 
ridges and interspaces covered by numerous, on the type twenty-five, 
narrow spiral striations ; incremental lines indistinct. Aperture sub- 
circular to nearly square. Dimensions : Maximum diameter, 16 mm. ; 
height unknown. 

Occurrence. — At locality 2283, northeast of Coalinga, near middle 
of Santa Margarita; locality 1697, about one-half mile north of town 
of Santa Margarita, in type section of the Santa Margarita. 

TURRITELLA MARGARITANA, n. sp. 
Plate 20, figure 5 

Type specimen, no. 11312, in Univ. Calif. Coll. Invert. Palae., from locality 
1706 at approximately middle of southern boundary of sec. 17, T. 29 S, R. 13 
E, M. D. B. & M. ; elevation about 1200 feet. San Luis quadrangle. 

Shell medium in size ; number of whorls unknown ; sides of whorls 
approximately flat ; suture distinctly impressed. Near the base are 



1917] Nomland : Fauna of the Santa Margarita Beds 



313 



two heavy ribs, the upper being more prominent, the interspaces 
between these about the same width as the ribs ; the rib next to the 
suture above of about same prominence as two near base ; between 
the ribs at base and the one at top are two spiral lines with narrow 
interspaces. Incremental lines nearly invisible. Aperture quad- 
rangular to subcircular. Dimensions : Maximum diameter, about 14 
mm. ; height unknown. 

Occurrence. — At localities 1697, 1706, north of town of Santa 
Margarita, type section of the formation, San Luis Obispo County. 
This species occurs at the type locality with Turritella freya, n. sp. 



EXPLANATION OF PLATE 14 
All figures approximately natural size. 
Fig. 1. Mytilus kewi No inland. Occurrence, in lower Etehegoin and Santa 
Margarita. 

Fig. 2a. Amiantis communis, n. sp. Left valve; type specimen no. 11311; 
U. C. locality 2276; Santa Margarita. 

Fig. 2b. Amiantis communis, n. sp. View showing lunule and escutcheon of 
same specimen as figure 2a. 

Fig. 2c. Amiantis communis, n. sp. Interior view of right valve ; from locality 
2276. 

Fig. 2c?. Amiantis communis, n. sp. Interior view of left valve ; locality 2276. 



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UNIV. CALIF. PUBL. BULL. DEPT. GEOL. [NOMLAND] VOL. 10, PLATE 14 




EXPLANATION OF PLATE 15 
All figures approximately natural size. 
Fig. la. Pinna bicuneata, n. sp. View of right valve of type specimen 11307; 
from U. C. locality 2284; characteristic of upper San Pablo and Santa Mar- 
garita. 

Fig. lb. Pinna bicuneata, n. sp. Profile of both valves as viewed from the 
rear. 

Fig. 2a. Chione semiplicata, n. sp. Exterior view of left valve of type speci- 
men no. 11318; from U. C. locality 2283; Santa Margarita. 

Fig. 25. Chione semiplicata, n. sp. Interior view of left valve. 
Fig. 2c. Chione semiplicata, n. sp. View of interior of right valve. 



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UNIV. CALIF, PUBL. BULL, DEPT. GEOL 



[NOMLAND] VOL. 10, PL, 15 




EXPLANATION OF PLATE 16 

Fig. 1. Ostrea titan corrugata, n. var. Exterior view of lower valve ; Univ. 
Calif. Coll. Invert. Palae., type specimen no. 11309; locality 2284; Santa Mar- 
garita. Approximately three-fifths natural size. 



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[NOMLAND] VOL. 10, PL. 16 




EXPLANATION OF PLATE 17 

Fig. 1. Ostrca titan corrugata, n. var. Interior view of lower valve; type 
specimen no. 11309; from U. C. locality 2284; Santa Margarita. Approximately 
three-fifths natural size. 



[320] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL. 



[NOMLAND] VOL. 10, PL. 17 




EXPLANATION OF PLATE 18 
All figures approximately natural size. 
Fig. 1. Pecten crassicardo biformatus, n. var. Exterior view of left valve ; 
Univ. Calif. Coll. Invert. Palae. type specimen no. 11308; locality 3029; Santa 
Margarita. 

Fig. la. Pecten crassicardo biformatus, n. var. View of left valve showing 
narrow ribs. 

Fig. lb. Pecten crassicardo biformatus, n. var. Eight valve of same speci- 
men as figure la. 



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UNIV. CALIF. PUBL. BULL. DEPT. GEOL. 



[NOMLAND] VOL. 10, PL. 18 




EXPLANATION OF PLATE 19 
All figures approximately natural size. 

Fig. la. Purpura nanna, n. sp. Back view of type specimen no. 11315; from 
U. C. locality 2279; Santa Margarita. 

Fig. 16. Purpura nanna, n. sp. Mouth view of same specimen as figure la. 

Fig. 2. Turritella freya, n. sp. Upright view of type specimen, Univ. Calif. 
Coll. Invert. Palae. no. 11313. Characteristic of the Santa Margarita. 

Fig. 3a. Acantldna (Monoccras) noma, n. sp. Mouth view of an excellently 
preserved specimen; type specimen no. 11314; U. C. locality 2276; Santa Mar- 
garita. 

Fig. 36. Acanthina (Monoccras) noma, n. sp. Back view of same specimen 
as figure 3 a. 

Fig. 4. Pectcn crassicardo biformatus, n. var. Profile of type specimen. 

Fig. 5. Septifer margaritana, n. sp. Exterior of right valve of type no. 
11310; U. C. locality 2276; Santa Margarita. 

Fig. 6. Periploma clarlii, n. sp. Left valve of imperfect type specimen no. 
11320; from U. C. locality 2278; Santa Margarita. 



[324] 



UNIV. CALIF. PUBL, BULL. DEPT. GEOL, 



[NCMLAND] VOL. 10, PL, 19 




EXPLANATION OF PLATE 20 
All figures approximately natural size. 
Fig. 1. Trophon perelegans, n. sp. Back view of type specimen no. 11321; 
Santa Margarita. 

Fig. 2. Trophon perelegans, n. sp. Mouth view of a small specimen. 

Fig. 3. Trophon perelegans, n. sp. Back view showing prominent varices. 

Fig. 4a. Tegula varistriata, n. sp. Back view of type specimen no. 11316; 
characteristic of Santa Margarita. 

Fig. 4:0. Tegula varistriata, n. sp. View of aperture and umbilicus of same 
specimen as figure 4a. 

Fig. 5. Turritella margaritana, n. sp. Upright view of specimen no. 11312; 
from type section of the Santa Margarita formation. 

Fig. 6. Tegula thea, n. sp. Back view of type no. 11317; showing shoulder 
and prominent ribbing. 

Fig. 7a. Tegula thea, n. sp. Back view of a small specimen. 

Fig. 76. Tegula thea, n. sp. Basal view of same specimen as figure 7a. 

Fig. 8. Siphonalia danvillensis Clark. Bear view of specimen from Santa 
Margarita, north of Coalinga. 

Fig. 9. Siphon-aim danvillensis Clark. Bear view of type described from 
San Pablo group. 

Fig. 10. Fusinus fabulator, n. sp. Upright view of type specimen no. 11319 ; 
U. C. locality 3029, Santa Margarita, Tejon Hills. 



[326] 



UNIV. CALIF. PUBL, BULL. DEPT. GEOL. 



[NOMLAND] VOL. 10, PL. 20 




UNIVERSITY OF CALIFORNIA PUBLICATIONS 

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Vol. 10, No. 19, pp. 327-360, pis. 21-24 



Issued October 17, 1917 



MINERALS ASSOCIATED WITH THE CRYSTAL- 
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BY 

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UNIVERSITY OF CALIFORNIA PRESS 
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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 19, pp. 327-360, pis. 21-24 Issued October 17, 1917 



MINERALS ASSOCIATED WITH THE CRYSTAL- 
LINE LIMESTONE AT CRESTMORE, 
RIVERSIDE COUNTY, 
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L NOV 5 



BY \ 

AETHUE S. EAKLE 



CONTENTS 

PAGE 

Description of the rocks 328 

Igneous intrusives and metamorphism 328 

Hills and quarries 329 

Intrusive rocks 329 

The limestone 330 

Metamorphism of the limestone 331 

Description of the minerals 332 

Minerals disseminated in the white limestone of Chino Hill 332 

Brucite 332 

Hydromagnesite 333 

Chondrodite 333 

Graphite 333 

Phlogopite 334 

Serpentine 334 

Minerals in the contact zones of Sky Blue Hill 334 

Blue calcite 334 

Wollastonite 334 

Vesuvianite 338 

Garnet 339 

Diopside 340 

Xanthophyllite, var. waluewite 341 

Monticellite 342 

Wilkeite 343 

Crestmoreite, a new mineral '. 344 

Eiversideite, a new mineral 347 

Clinoehlore 348 

Apatite 348 

Aragonite 348 



328 University of California Publications in Geology [Vol. 10 

PAGE 

Minerals associated with the intrusives 349 

Feldspars 349 

Augite 349 

Hornblende and biotite 349 

Titanite _ _ 349 

Zircon 349 

Epidote 349 

Quartz '. 350 

Tourmaline 350 

Axinite 350 

Datolite 350 

Scapolite 350 

Apophyllite 350 

Okenite 351 

Prehnite 351 

Laumontite 352 

Opal 352 

Sulphide minerals 352 

Oxydation products 353 



Description op the Rocks 
igneous inteusives and metamorpiiism 

At Crestmore, about eight miles westerly from Riverside, there is 
an isolated mass of granodiorite with a capping of crystalline limestone 
which is of exceptional interest because of the many minerals developed 
in the limestone by contact and hydrothermal metamorphism. 

The Riverside Portland Cement Company's plant, situated at the 
base of the hill, uses both rocks in the manufacture of cement. The 
extensive quarrying is rapidly destroying the hills, and the different 
minerals and associations almost daily brought to view are immediately 
carted to the rock-crushers, so that a vast amount of material of 
scientific value and many fine specimens are lost. 

The writer visited the quarries a few years ago and collected much 
of the material described here, but no detailed study of the deposits 
was made and no opportunity has presented itself for a second visit. 
Specimens have been collected by others and sent to the University, 
which have been of great help in making the list complete, and special 
thanks are due Mr. L. J. Childs of Rialto. He has kept in touch with 
the quarrying and collected minerals that otherwise would have been 
lost, and these with notes of their occurrence have been given to the 
writer. About fifty minerals are described in this paper, but these 
represent only a portion of what probably could be found by daily 



1917] Eaklc: Minerals Associated ivith Crystalline Limestone 329 



visits. The cement contains the calcined remains of many beautiful, 
rare, and perhaps new, mineral species. 

Hills and Quarries. — The Crestmore limestone forms two hills 
closely connected by a saddle-ridge. Both hills rest upon a common 
base of granodiorite somewhat elliptical in contour, with its longer axis 
trending northeast-southwest. The north is called Sky Blue Hill 
because of its blue calcite ; while the south hill, having pure white 
marble, has been designated Chino Hill. Sky Blue Hill has a large 
quarry on its northern side called North Star quarry, a larger one on 
its eastern side named the Commercial Rock quarry, and between them 
a third one, the Lone Star quarry, has recently been opened. Chino 
Hill has one large quarry on its southwest side, and the accompanying 
view (pi. 21) shows this quarry and the plant of the cement company. 
The floor of the quarry marks approximately the juncture of the 
igneous base with the limestone capping. 

The limestone forming the capping is a small remnant of a more 
extensive body of limestone which formerly covered this region. There 
is a larger mass similar to Crestmore about three miles west, and Slover 
Mountain near Colton may be another remnant left as a capping upon 
an intrusive mass. 

Intrusive Rocks. — There are three types of igneous intrusives occur- 
ring in the hills and all three have been active agents in the meta- 
morphism of the limestone. Granodiorite, quartz-monzonite porphyry 
and pegmatite are present and intimately associated with the contact 
phenomena. 

The granodiorite is a hornblende-biotite rock with a fairly coarse 
granitic structure consisting essentially of orthoclase, plagioclase, 
hornblende, biotite, and quartz. The orthoclase, which appears to 
constitute the main portion of the rock, is mostly white, and the rock 
is consequently gray as the prevailing color, but patches of brick-red 
orthoclase occur, giving the rock a red color. Labradorite and oligo- 
clase are the triclinic feldspars present, but very little albite twinning 
is seen. The rock is not fresh and all of the feldspars are muddy and 
opaque. The dark silicates are mostly black hornblende, which is 
dark green in thin section, and a few plates of biotite. Quartz is much 
subordinate to the feldspars in amount. 

This granodiorite is used by the company as a substitute for clay 
in the cement. Daily analyses of it are made and three of them will 
serve to show the relative proportions of the bases. 



330 University of California Publications in Geology [Vol. 1° 



Si0 2 


60.60% 


60.78% 


60.30% 


AL0 3 


16.61 


16.04 


16.03 


Fe 2 3 


5.03 


4.82 


4.19 


CaO 


7.93 


8.22 


7.19 


MgO 


2.08 


1.99 


2.26 


Loss 


4.79 


4.75 


4.42 




97.08 


96.60 


94.39 



The alkalies are not determined in these analyses. Probably some 
potash and soda have been leached out in the alteration of the feld- 
spars. The granodiorite has its best exposure on Chino Hill and is 
plainly seen underlying the white limestone. The rock is mined by 
tunnels into it from the side of the hill below the limestone. 

The quartz-monzonite porphyry forms dikes and laccolithic-shaped 
masses in the limestone of Sky Blue Hill. The rock is very fine- 
grained, almost felsitic in character, with an ash-gray color. Under 
the microscope it is essentially a fine granular mixture of quartz, 
orthoclase and plagioclase with occasional large plates of feldspar and 
angite. Some pale green and slightly pleoehroic hornblende is present, 
but most of the dark magnesian mineral is augite. It occurs in 
granular aggregates 1 a pale bluish-green color and shows no pleo- 
chroism. Titanite grains are common in the rock. 

This rock forms a wide intrusion into the limestone of Sky Blue 
Hill, since tunnels run into the hill from the floor of the Commercial 
Rock quarry penetrate it for several hundred feet. It has been the 
most active agent in the formation of the metamorphic minerals of 
this hill. 

The pegmatite occurs as intrusive dikes but it is difficult to trace out 
their boundaries. They appear to be associated more with the meta- 
morphic masses of vesuvianite-garnet rock. The pegmatite consists 
mainly of white orthoclase and green epidote. Orthoclase occurs in 
large cleavage masses and is usually pure white in color. The epidote 
penetrates the feldspathic mass in long slender crystals, most of which 
are altered to a bronze-brown color. Quartz occurs as smoky granular 
masses but is not prominent. Zircon, tourmaline, axinite, pyroxene, 
and a few other minerals are occasionally found as accessories and 
some minerals have later been developed in the pegmatites by hydro- 
thermal metamorphism. 

The Limestone. — Daily analyses are made of the limestone and that 
from the Chino quarry has the following average compositions : 



1 91 7] Eaklc: Minerals Associated ivith Crystalline Limestone 331 



SiO, 
E 2 3 
CaO 
MgO 



Loss 



4.50% 

1.20 
50.78 

2.50 
40.60 



4.68% 

1.24 
50.85 

2.25 
40.36 



4.26% 

1.66 
50.00 

2.54 
41.54 



5.24% 

1.40 
50.33 

2.60 
40.40 



99.58 



99.38 



100.00 



99.97 



Analyses show that about two and one-half per cent of magnesia is 
the average amount of that oxide in the white limestone or marble, and 
it is therefore not very dolomitic. Associated with, and merging into 
this rock are masses of similar white crystalline limestone containing 
much magnesia, as the mineral brucite, disseminated through it in 
pisolitic-shaped inclusions. The brucite rock apparently overlies the 
other limestone, and is seen very prominently on the south end of 
Chino Hill and near the surface in the Commercial Rock quarry on 
Sky Blue Hill. It may be a remnant of a separate and distinct bed 
of magnesian limestone, but the amount of the brucite varies consider- 
ably and it has evidently been formed from some other magnesium 
mineral, whose origin was due to contact metamorphism, and the 
source of the magnesia might have been in the solutions accompanying 
such metamorphism. 

Metamorphism of the Limestone. — The two hills are utterly dis- 
similar in the effects of metamorphism. The limestone of Chino Hill 
was converted into a white marble with very little development of 
included metamorphic minerals. It does not appear to have suffered 
successive metamorphism and recrystallization as would be induced by 
later injections of igneous rock, and the original intrusion of the 
granodiorite accounts for its simple metamorphism. At the south end 
of the quarry the rock grades into a brucite-graphite limestone ; and 
the brucite and graphite are so thickly disseminated as to warrant the 
assumption that the original rock was a highly carbonaceous, mag- 
nesia-bearing limestone which, by metamorphism, became converted 
into a mixture of calcite, periclase, and graphite, the periclase subse- 
quently altering to brucite. 

The Sky Blue Hill portion of the limestone capping was subjected 
to later and more intensified metamorphism by intrusions of the 
quartz-monzonite and pegmatite, and by the hydrothermal action of 
the silicated-carbonated solutions accompanying or following these 
intrusions. Practically all of the minerals developed are products of 
hydrothermal metamorphism. These solutions also carried phosphates 



332 University of California Publications in Geology [Vol.10 



and small amounts of metallic sulphides. The beautiful blue calcite 
occurring only in the north hill is a recrystallization by these solutions, 
and some of the minerals, like the brucite, apophyllite, okenite, crest- 
moreite, prehnite, laumontite, etc., have been formed by the action of 
such solutions on pre-existing minerals. 

Zones or bands of contact metamorphic silicates separate the white 
crystalline marble from the dikes of monzonite and pegmatite, and 
some of the material is a compact massive and inseparable mixture. 
Vesuvianite, garnet, and wollastonite are the abundant silicates of 
Sky Blue Hill. Plate 22 shows three views of the Commercial Rock 
quarry on this hill. 

Description op the Minerals 

MINERALS DISSEMINATED IN THE WHITE LIMESTONE 
OF CIIINO HILL 

Brucite. — The magnesia hydrate is not disseminated through the 
limestone as plates or scales but occurs wholly in rounded, pisolitic 
bodies. The pisolites are generally quite prominent because of their 
gray, yellow or pink color in contrast to the white calcite. Magnified 
sections show them to be composed of a congeries of thin, overlapping, 
curved plates and threads, more or less concentrically arranged, and 
with a cross-fibered structure. This internal structure indicates great 
strain and pressure in their formation, and little can be made of them 
optically. The general interference colors are low, but their com- 
pressed, interwoven fibrous structure prevents extinction. An analyses 
of the pisolites gave : 



Some of the brucite is deeply colored by ferric oxide, which imparts a 
yellow and red spotted appearance to the white limestone. Near the 
surface of the hill in the Commercial Rock quarry, where the brucite 
ha.s been weathered out, the limestone is cellular, with the cavities 
lined with the yellow or red oxide. 

Periclase is assumed to be the original mineral which has changed 
to brucite by simple hydration. No periclase has been observed and 
no other mineral occurs in the limestone from which brucite could 
be derived. The very regular form of the pisolites suggests an 



MgO 
Fe,0 3 
ILO 



67.48% 

0.55 
31.73 



99.76 



G = 2.39 



1917] Eaklc: Minerals Associated with Crystalline Limestone 333 

original isometric crystal with an octahedral shape such as periclase 
would have had. The internal structure of the hrucite clearly indi- 
cates that they have formed under great pressure, such as would be 
produced by expansion within a confined space. In a change from the 
anhydrous periclase to the hydrous brucite an increase in volume of 
nearly two and one-half times that of the periclase is necessary under 
normal conditions, and this great swelling has caused sufficient pres- 
sure not only to produce the twisted and fibrous internal structure of 
the pisolites, but also to curve slightly the twinning planes of the 
calcite bordering the cavities. 

The names predazzite and pencatite were given to a similar brucite 
limestone from Predazzo in the classic Monzoni district of Tyrol. 
Specimens of the predazzite show the same compressed and strained 
brucites in the white limestone, and they have generally been held to 
be brucite derived from periclase, and some unaltered periclase has 
been found. Lanacek 1 holds from a petrographic study of the predaz- 
zite that the pisolites are hydromagnesite rather than brucite. Some 
of the brucite of the Crestmore limestone is altered to hydromagnesite 
as a later change but the pisolites are in the main brucite, as shown by 
the analysis. 

Hydromagnesite. — Some of the brucite pisolites have altered by 
weathering into earthy white material which qualitative tests prove 
to be the hydrocarbonate of magnesia. It is evidently secondary from 
brucite and not from any periclase direct. 

Chondrocyte. — This is the only mineral in the list of which there 
is no well-authenticated proof of its existence in the quarries. Chon- 
drodite and its characteristic associate, spinel, might be expected 
among the products of metamorphism in the Commercial Rock quarry, 
but apparently fluorine was absent, as tests of the spotted limestone 
which suggest chondrodite failed to show its presence. Specimens of 
chondrodite have been collected from the Colton limestone. Brucite 
may form from chondrodite but it much more probable that periclase 
was the original mineral of the Crestmore rock. 

Graphite. — The only place in the quarries where graphite is promi- 
nent in the limestone is on the south end of Chino Hill, in close asso- 
ciation with the brucite. It is so thickly disseminated through the 
limestone as small flakes and scales that the rock is of a dark gray 
color in consequence. The pisolites of brucite are often surrounded 
by a border of black graphite, probably so oriented by the solutions 

i Min. u. petr. Mitth., vol. 12, pp. 429, 447, 1892. 



334 



University of California Publications in Geology [Vol. 10 



causing the change from periclase to brucite. Graphite was not promi- 
nent in the quarries on Sky Blue Hill. 

Phlogopiie. — A few flakes of brown phlogopite mica nave been 
observed in the white limestone of Chino Hill. 

Serpentine. — Very little serpentine has been found on either hill. 
A few small patches and streaks occur here and there in the white 
marble of the Chino quarry. 

MINERALS IN THE CONTACT ZONES OF SKY BLUE HILL 

Blue Calcite. — The blue calcite occurs only in the Commercial Rock 
quarry. Some of it is intensely blue, especially when freshly exposed, 
but it fades somewhat to more of a sky-blue color. It does not occur as 
one large mass of blue calcite, but rather as seams, bands, and patches 
intimately mixed with the various metamorphic minerals. When the 
quarry was first opened the blue calcite was very common and was 
used for road rock and in sugar refining, but very little is now seen. 
It is one of the contact metamorphic minerals ; and in the recrystal- 
lization of the carbonate larger rhombohedrons have resulted, some of 
the cleavage rhombohedrons measuring four to five centimeters in 
diameter. The cause of the blue color has not been determined, but is 
believed to be due to minute inclusions of carbonaceous matter. Slight 
heat completely decolorizes it. This blue calcite forms the matrix for 
wilkeite, crestmoreite, xanthophyllite, and monticellite, and contains, 
besides, minute crystals of vesuvianite and diopside. Pale green and 
pale pink specimens of calcite are occasionally seen, but the prevailing 
colors are blue and white. 

Wollastonite. — The calcium silicate has been most abundantly 
formed in the limestone, especially on Sky Blue Hill. It forms great 
masses in the North Star quarry and tons of it can be obtained. Four 
structural types or habits may be ascribed to the Crestmore wollas- 
tonite. 

The first has the common reticulated columnar and fibrous struc- 
ture which is so characteristic of wollastonite. Crystals of this type 
are long, narrow and much striated, and generally show no end-faces. 
Masses of this kind of wollastonite have occasionally been encountered 
in the limestone of the Chino quarry. 

The second type is represented by large well-formed crystals having 
the forms and habit of the usual wollastonite crystals. Glassy white 
crystals, several centimeters long and more than a centimeter broad, 



1917] Eaklc: Minerals Associated with Crystalline Limestone 335 

occur in direct association with garnet and vesuvianite. They are 
elongated parallel to the &-axis and have one end terminated by fairly 
good faces. The forms observed on these crystals are : 

a (100) m (110) v (101) s (201) 

c (001) x (120) a (T02) p (111) new 

g (011) (320) t (T01) 

■ 

The orthopinacoid and base are broad while the domes are very 
narrow; this gives the crystals an appearance of elongated square 
prisms. One* crystal had a rough face of the front unit pyramid, 
which is a new form for wollastonite. Figure 1, plate 23, shows this 
type. The angles obtained with the two-circle goniometer and those 
calculated are as follows : 



Measured Calculated 



Forms 




<P 




P 




<t> 


P 


C 001 


90°00' 


5° 34' 


90°00' 


5° 30' 


a 100 


90 


00 


90 


00 


90 


00 


90 00 


m 110 


43 


40 


90 


00 


43 


39 


90 00 


x 120 


25 


31 


90 


00 


25 


30 


90 00 


s 320 


55 


10 


90 


00 


55 


03 


90 00 


v 101 


90 


00 


45 


21 


90 


00 


45 35 


a T02 


90 


00 


19 


36 


90 


00 


M 03 


t T01 


90 


00 


39 


13 


90 


00 


39 35 


S 201 


90 


00 


60 


03 


90 


00 


60 14 


g on 


4 


42 


46 


36 


5 


39 


44 12 


p in 


47 


10 


53 


36 


46 


29 


54 34 



The third structural type is granular and very unusual for wol- 
lastonite. Large masses of snow-white, fine-granular wollastonite 
occur in the white limestone of the North Star quarry of Sky Blue 
Hill. The material is loosely coherent and friable ; specimens can 
readily be crushed between the fingers into fine grit and glassy grains. 
An analysis of this unusual variety gave the composition : 

Si0 2 51.77% 
Fe,.0 3 2.12 

CaO 44.85 
Ign. 1.02 

99.76 

The general tendency of wollastonite is to crystallize in long 
columnar forms ; when found occurring as a fine granular mass it 
must mean a peculiar condition of crystallization. Wollastonite 
usually occurs imbedded in limestone as inclusions, but massive 
boulders of this granular variety are quarried containing no associated 



336 University of California Publications in Geology [Vol. 10 



calcite. This friable granular variety has every appearance of having 
been thrown down as crystalline precipitated granules from a cooled 
saturated solution of the lime silicate. The precipitate was crystalline 
as every grain is transparent glassy, but the imperfectly formed 
crystals were not cemented into a compact mass which would have 
been ordinarily the case in a dense crystallization such as this implies. 
Presumably this mass, which seems to be a large segregation in the 
limestone, was formed by rapid crystallization and sudden precipita- 
tion from a solution whose temperature was rapidly lowered. This 
variety is only found on the northern end of the hill and at some 
distance from the intrusive dikes. 

The fourth type consists of distinct crystals which have formed 
by later silica solutions acting upon the limestone in the vicinity of the 
pegmatite dikes and on the outer border of the contact zones. Acicular 
and slender crystals with terminations on one end occur associated 
with apophyllite and okenite. The crystals are clear and colorless, 
with bright lustrous faces. By pressure they separate into silky fibers. 
They possess perfect orthopinacoidal cleavage and have the usual 
elongation parallel to the ?>-axis. Twenty-three forms were observed, 
of which twelve were new, as follows : 

c (001) v (101) g (Oil) u (T44) new 

a (100) r (104) new p (744) new <p (122) 

I (740) new 6 (T04) new o (344) new ^ (T22) 

h (540) (T03) n (144) new u, (142) new 

q (340) a (T02) b (744) new e (T42) new 

m (140) new t (T01) i (344) new 

The crystals are slender and consequently the dome faces are nar- 
row and apt to be striated. The base, orthopinacoid and three domes 
vat are common to all the crystals. One crystal gave readings for 
narrow but distinct forms corresponding to two new domes (104) and 
(T04) . The end terminations of the crystals are remarkable. The unit 
prism (110) and elinoprism (120), which are common forms on wol- 
lastonite, are absent, and a new prism (140) predominates; the prisms 
(540) and (340), known forms but very rare, are common on these 
crystals. The pyramidal forms are likewise remarkable in showing a 
similar odd series of symbols and no forms common to the usual 
crystals of wollastonite. Practically all of the pyramids are new 
forms. The forms (144) and (144) are common on all, with (344) 
and (344) usually present. Two of the crystals have small faces of 
the forms (744) and (744). The forms (544) and (544), which 



1917 j Eakle: Minerals Associated with Crystalline Limestone 337 



would complete the two odd series, may also be present, as some 
approximate readings indicated them, but their occurrence could not 
be established with absolute certainty. Two very small and poor faces 
corresponding to the forms (122) and (T22) and a line face of (Oil) 
occur. The two new forms (142) and (T42) were line faces and gave 
only approximate measurements. 

Another unique fact about these crystals is that for every positive 
pyramid there is a negative one with like symbols ; but the symbols for 
the rear faces do not correspond to the front ones. It is characteristic 
that the crystals have three or four prism faces on their ends each 
representing a different form. Figures 2 and 3, plate 23, show the 
combinations on some of the crystals. Figure 3 shows the end of the 
crystals with the rear faces drawn in the left half in reversed position. 
Figures 4 and 5 are orthographic projections on the clinopinacoid 
which bring out better the combination of faces. 

Only one end of the crystals is terminated, sometimes the right and 
again the left end. The disposition of the faces indicates a lower grade 
of symmetry as there is no apparent axis of symmetry, and the 
crystals could belong to the hemimorphic class of the monoclinic sys- 
tem, or to the triclinic system. The mineral is strongly tribo-lum- 
inescent and this physical property is an evidence of a more complex 
molecular structure. The dome faces on these crystals are identical 
with those of all wollastonite crystals, but the terminated ends are 
totally dissimilar. 







Measured 






Calculi 


ited 




No. of 


Forms 




P 


P 






P 




measurements 


C 001 


90°00' 


5°30' 


90°00' 


5° 30' 


25 


a 100 


90 


00 


90 


00 


90 


00 


90 


00 


30 


I 740 


59 


03 


90 


00 


59 


04 


90 


00 


7 


h 540 


49 


57 


90 


00 


50 


01 


90 


00 


8 


q 340 


35 


35 


90 


00 


35 


35 


90 


00 


10 


m 140 


13 


25 


90 


00 


13 


25 


90 


00 


13 


v 101 


90 


00 


45 


33 


90 


00 


45 


33 


22 


t 104 


90 


00 


18 


35 


90 


00 


18 


07 


1 


e T04 


90 


00 


7 


41 


90 


00 


7 


40 


1 


k T03 


90 


00 


11 


36 


90 


00 


11 


56 


1 


a T02 


90 


00 


20 


00 


90 


00 


20 


00 


19 


t T01 


90 


00 


39 


33 


90 


00 


39 


35 


24 


g on 


5 


12 


45 


44 


5 


41 


44 


12 


1 


p 744 


60 


29 


62 


19 


60 


31 


63 


03 


3 


o 344 


38 


59 


51 


16 


39 


10 


51 


19 


6 


n 144 


18 


33 


45 


33 


18 


40 


45 


37 


11 


b 744 


58 


20 


61 


41 


57 


30 


60 


58 


2 


i 344 


3T 


42 


48 


37 


3T 


38 


48 


39 


7 



338 University of California Publications in Geology [Vol. 10 





Measured 




Calculated 


No. of 


Forms 





P 


< 


P 


P 


measurements 


u T44 


8 09 


44 16 


7 


55 


44 19 


11 


122 


30 38 


47 24 


28 


57 


48 09 


1 


fa 122 


19 02 


45 14 


20 


41 


45 58 ' 


1 


w 142 


15 35 


62 51 . 


16 


05 


63 35 


1 


e T42 


IT 04 


62 57 


To 


41 


63 05 


1 



Aii analysis of the clear crystals gave : 

SiO, 50.42% 

CaO 48.29 
MgO 0.60 
Fe,0 3 0.51 
Ign. 0.07 

99.89 

The optical data were kindly determined by E. S. Larson of the 
U. S. Geological Survey: 

a = 1.614; /3= 1.629; -, = 1.631; 2E = 58°±'5°; 2V = 35°±4°; 
Y II fibers; Z 1 fibers. Parallel extinction; dispersion per- 
ceptible p>i>. 

The indices are close to those for pure artificial wollastonite : 
o = 1.616; /3 = 1.629; y = 1.6321; 2V = 39°. 

Vesuvianite. — Massive vesuvianite is very common in the meta- 
morphic zones between the monzonite dikes and limestone. It is in- 
timately associated with garnet and diopside. Most of this massive 
variety has a light yellowish color and shows broad crystal faces. 
Simple crystals of this yellow color are also common, some of them 
being very perfect. The blue caleite contains crystals of a darker 
brown color with brilliant faces and somewhat fused appearance. 

Two general habits of the crystals are prominent. The simpler 
type consists of the doubly terminated pyramid without any modifying 
faces on the edges, as illustrated in figure 6, plate 24. Occasionally 
the edges of these are truncated by the second-order pyramid as 
narrow faces, and a small base may also be present. The sizes of these 
crystals range from less than one-fourth centimeter to more than six 
centimeters in width. All of them are of the light yellow color and 
they are associated with the white crystalline limestone. 

The second type consists mainly of the unit bipyramid (111) and 
second-order prism (100) in about equal development, as shown in 
figure 7. This type is often modified by very small planes on the edges 
and on the points of the lateral axes, making a more general combina- 
tion, as illustrated in figure 8. These crystals have a dark brown 



1917] Eakle: Minerals Associated with Crystalline Limestone 339 



brilliant surface, with lighter brown interiors, and they occur imbedded 

in the blue calcite in association with the wilkeite. 

The small faces grouped about the ends of the axes are often 

rounded and give readings which yield improbable symbols, but the 

ones identified are : 

c (001) p (111) y (441) 

a (010) b (221) s (131) 

m (110) i (331) i (132) 

o (011) z (121) n (154) new 

b (285)? 

The new form (154) occurs on several of the crystals; the narrow 
face of (132) rounded into a narrow face which gives a good reflection 
and corresponds to the symbol (285), but it is not repeated on any 
other crystal and must be classed as doubtful. 

The measured and calculated angles are as follows : 

Measured Calculated 



Forms 


1 


P 




P 




<P 


P 


c 001 


0°00' 


0°00' 


0°00' 


0°00' 


a 010 


90 


00 





00 


90 


00 


00 


m 110 


44 


50 


89 


50 


45 


00 


90 00 


o 011 





00 


28 


20 





00 


28 15 


p 111 


44 


55 


37 


11 


45 


00 


37 14 


b 221 


44 


56 


56 


43 


45 


00 


56 40 


t 331 


45 


00 


66 


19 


45 


00 


66 19 


s 121 


26 


19 


49 


56 


26 


34 


50 14 


s 131 


18 


30 


59 


30 


18 


26 


59 32 


i 132 


18 


31 


40 


23 


18 


26 


40 22 


n 154 


11 


00 


34 


30 


11 


18 


34 25 


b 285 


14 


30 


41 


55 


14 


03 


41 34 



An analysis of the green vesuvianite by J. B. Wright gave : 



Si0 2 


36.88% 


ALA 


17.61 


FeA 


3.11 


FeO 


0.46 


MnO 


1.50 


CuO 


1.06 


CaO 


33.27 


MgO 


4.73 


Na,0 


0.34 


H 2 


0.61 




99.57 



G = 3.36 

Garnet. — The cinnamon-colored grossularite is abundant in asso- 
ciation with the vesuvianite. Most of it is compact massive and shows 



340 University of California Publications in Geology [Vol. 10 



only an occasional broad face of the dodecahedron. Good crystals also 
occur and some of the rhombic dodecahedrons measure ten centi- 
meters in diameter. All of those collected are simple dodecahedrons 
without other forms. Some of the crystals are mere shells of garnet 
enclosing a center of white calcite. 

The massive grossularite was analyzed by J. B. Wright with the 
following result : 



SiO, 


35.53% 


A1 2 3 


21.11 


Fe 2 3 


3.95 


FeO 


0.60 


CuO 


0.70 


CaO 


36.06 


MgO 


0.78 


Na.O 


0.20 


H 2 


1.23 




100.15 



G = 3.39 

Granular yellow garnet and dark brown massive varieties also 
occur, apparently in connection with the pegmatite dikes. No analyses 
of them have been made to determine the particular species. 

Diopside. — Associated with garnet in the zone of metamorphic lime 
silicates, a deep green massive pyroxene occurs, which is probably a 
diopside of a darker color than the crystals scattered through the 
calcite. All of the crystals are of a pale yellowish green color and 
occur as single crystals imbedded in the blue calcite. Most of them 
are small, only a few millimeters long, but some have been found four 
centimeters in length. They are all of one general type : short prisms 
tapering off by a succession of unit pyramids to pointed ends, with or 
without small basal planes. Figures 9 and 10, plate 24, show this 
general habit and some of the combinations. The observed forms are : 

c (001) e (011 j X (331) d (131) 

a (100) z (021) o (221) M (121) 

b (010) v (221) * (Til) t (211) 

m (110) u (111) t (T12) e (T21) 

tt (231) new 

The new form truncates the edge (110) (121) and occurs on several 
crystals. The edges have manj' rounded faces and some of the symbols 
corresponding to them are given unlettered in the following table of 
measurements and calculations. They are doubtful forms. 



1917] Eakle: Minerals Associated with Crystalline Limestone 341 



Measured Calculated 



Forms 


<t> 


p 


<P 


p 


C 001 


90°00' 


15°50' 


90° 00' 


15°50' 


b 010 


00 


90 00 


00 


90 00 


a 100 


90 00 


90 00 


90 00 


90 00 


m 110 


43 34 


90 00 


43 33 


90 00 


e Oil 


25 40 


32 58 


25 43 


33 11 


S 021 


13 29 


50 30 


13 32 


50 29 


u 111 


55 04 


45 55 


55 04 


45 50 


v 221 


49 45 


61 40 


49 59 


61 23 


f T12 


T 11 


16 51 


44 


16 25 


8 Til 


25 12 


33 05 


25 07 


33 04 


221 


35 32 


55 23 


35 22 


55 19 


\ 331 


38 17 


66 12 


38 19 


66 04 


d 131 


25 27 


62 42 


25 31 


62 58 


,u 121 


35 37 


55 29 


35 36 


55 24 


it 231 


25" 27 


62 41 


25 19 


62 55 


( 211 


55 04 


45 41 


55 04 


45 50 


e T21 


13 53 


50 27 


13 12 


50 27 


352 


20 18 


57 07 


20 24 


57 36 


753 


45 20 


55 09 


46 11 


54 50 


836 


57 49 


29 14 


57 32 


28 47 


14.3.10 


69 57 


27 41 


7(7 32 


27 57 


10.12.7 


27 01 


48 18 


27 04 


48 37 



Xanthophyllite, var. waluewite. — The rare brittle-mica xantho- 
phyllite with its associate monticellite from Crestmore has recently been 
described by the writer, 2 so only the main facts concerning the min- 
erals will be incorporated here. Xanthophyllite was first described 
and named by Gustave Rose 3 as a wax-yellow mineral in scales and 
plates, occurring as a constituent of a talc-schist in the Shiskimskaya 
Mountains in the Urals. Years later the green variety was found and 
named waluewite by Kokscharof. 4 The waluewite or valuevite occurs 
as a constituent of chlorite schist in the Nicolai-Maximilian mine, 
near Slatoust in the Urals. These two occurrences are apparently the 
only ones reported and in both cases the mineral was a schist con- 
stituent. The Crestmore waluewite is a product of the contact meta- 
morphism and occurs disseminated through the blue calcite. Masses 
of the blue calcite speckled with the green waluewite were once very 
plentiful at the quarry, but none is now seen. 

The waluewite occurs in hexagonal-shaped basal plates of a deep 
grass-green color and vitreous to slight pearly luster. The plates are 

2 Jour. Wash. Acad. Sci., vol. 6, p. 332, 1916. 

a Pogg. Ann. d. Phys. und Chem., vol. 50, p. 654, 1840. Also in his Eeise nach 
dem Ural, vol. 2, pp. 120, 514, 527, 1842. 

4 Zeitschr. fur Kryst. vol, 2, p. 51, 1877. Also in his Mineral d. Euss., vol. 7, 
p. 346. 



342 University of California Publications in Geology [Vol. 10 



seldom grouped together and they average one-half centimeter broad 
and four millimeters thick. A few large ones have been found measur- 
ing several centimeters in width and thickness. While the basal planes 
are very brilliant the edges are dull, furrowed and impossible to 
measure. The thicker crystals show polysynthetic twinning like the 
micas and extinguish in striated sectors. Thin cleavage plates give a 
biaxial figure with an apparent optic angle of about twenty degrees. 
Measurements of the optic angle in sodium light showed a variation 
from twelve degrees to eighteen degrees. The plane of the optic angle 
is (100) and the mineral is negative. The refractive indices /3 and y 
in the basal section are practically the same, determined as 1.660. 

Several analyses of the waluewite from the Urals have been pub- 
lished and two of them are inserted here for comparison with the 
Crestmore mineral. 

No. 1. Waluewite from Crestmore. 

No. 2. Waluewite from Slatoust, Urals. Analyzed by Nikolajef.s 
No. 3. Waluewite from Slatoust, Urals. Analyzed by Clarke and 



Schneider. o 










1 


o 


3 


Si0 2 


16.74% 


16.39% 


16.85% 


Ti0 2 






tr. 


A1A 


42.70 


43.40 


42.33 


Fe,0, 


2.85 


1.57 


2.35 


FeO ' 


0.41 


0.10 


0.20 


CaO 


13.09 


13.04 


13.30 


MgO 


20.03 


20.38 


20.77 


Ign. 


4.49 


4.39 


4.60 




100.31 


99.77 


100.40 



G = 3.081 

Monticellite. — The blue caleite contains monticellite in small masses 
and grains scattered through it in close association with the waluewite. 
One large specimen from the quarry consists of a wide band of massive 
monticellite separated from the blue caleite by a thin seam of walue- 
wite plates, while the caleite has individual grains and plates, respec- 
tively, of the two minerals. 

The color of the monticellite is flesh or pale brown and the luster 
is somewhat greasy. The irregular grains show cleavage faces, but no 
crystals occur. The mineral is practically infusible and is soluble in 
acids, forming a gelatinous mass when boiled almost to dryness. 

s Zeitschr. fur Kryst., vol. 9, p. 579, 1885. Abstract. 
6 Amer. Jour. Sci., vol. 43, p. 379, 1892. 



1 917 ] Eakle: Minerals Associated ivith Crystalline Limestone 343 



Gordon Surr, 
analyst 



SiO, 
FeO 
CaO 
MgO 
Igu. 



36.02% 

2.82 
34.36 
24.74 

1.25 



37.46% 

2.94 
35.14 
25.32 



99.19 



100.86 



G = 3.078 



The occurrence of the monticellite and waluewite in close associa- 
tion is interesting because both have crystallized from the same silicate 
mixture and the waluewite may be viewed as having the composition of 
monticellite plus the spinel and alumina hydrate molecules. In the dis- 
cussion of the members of the clintonite group of silicates, Clarke and 
Schneider make the suggestion that waluewite may have the monti- 
cellite molecule in addition to its spinel and olivine molecules although 
no direct association of the two minerals was then known. Here we 
have the two crystallized together from a silicate mixture in which the 
monticellite molecule largely predominated and their crystallizations 
were practically simultaneous. The composition of the waluewite 
suggests a mineral mixture of monticellite -4- olivine -4- spinel -j- 
diaspore in an approximate ratio of 6:1:5:6. 

These monticellite and waluewite masses have in all probability 
been formed by the metamorphism of the brucite-limestone, while the 
common vesuvianite and diopside, which also occur in the blue calcite, 
but not associated with the monticellite and waluewite, are evidently 
products of metamorphism of the ordinary limestone, which has little 
magnesia. The former two were quite local in their development and 
were soon exhausted, while the latter are the abundant minerals of 
the quarry. 

Wilkeite. — This interesting lime mineral with the four acid radicals 
has already been described, 7 so only the essential parts of that descrip- 
tion will be given here. Boulders of blue calcite containing the 
granular pink wilkeite had just been blasted from the face of the 
quarry on the day the writer visited it, and fortunately specimens were 
collected of a mineral which would otherwise have gone unnoticed to 
the crusher. 

The wilkeite occurs as small grains and minute hexagonal prisms 
disseminated through the masses of blue calcite. The mineral is clear 

i Amer. Jour. Sci., vol. 37, p. 262, 1914. 



344 University of California Publications in Geology [Vol. 10 



and glassy and usually pink but some grains are yellow. The mineral 
is essentially a calcium phosphate of the apatite group, with much of 
the phosphate replaced by the silicate, sulphate and carbonate mole- 
cules. A summary of the properties of the mineral are : Hexagonal 
system ; c = 0.730 approx. Prominent forms ( 10T0 ) (1120) ( 10T1 ) and 
(0001). Imperfect basal cleavage. H = 5. G = 5.234. Color pale 
pink or yellow. Luster vitreous or greasy. Optically uniaxial, negative. 
n = 1.640 ± .005 ; n — n = .0004. 
Chemical composition is : 



Si0 2 


9.62% 


CaO 


54.44 


MnO 


0.77 




20.85 


so 3 


12.28 


CO, 


2.10 


ELO 


tr. 




100.06 



The formula derived from this analysis is : 

3Ca 3 (P0 4 ) 2 • 3Ca,Si0 4 . 3CaS0 4 . CaC0 3 . CaO. 
In order to better show its relation to apatite this may be written : 

3Ca 3 (P0 4 ) 2 . CaC0 3 + 3Ca 3 [(Si0 4 ) (S0 4 )] • CaO. 
During the past summer more of the wilkeite was observed in the 
quarry quite near the contact with the monzonite, in crystals several 
centimeters long, coated with its alteration product. This alteration 
substance coats the original grains and, in the absence of analyses, 
was thought to be okenite from its optical characters. There is a 
possibility that the delicate fibers optically tested are okenite ; they 
cannot be separated from the intermixed wilkeite and their exact 
composition cannot therefore be determined. Much white secondary 
material has more recently been found which, as analyses show, does 
not have the ratio of lime to silica in the proper proportions for okenite. 
Since it is different from any known silicate, it is described below as a 
new mineral. 

Crestmoreite, a New Mineral. — Since the appearance of the paper 
on wilkeite. blue calcite has been found in the Commercial Rock 
quarry containing much soft white material disseminated through it 
in small bunches, as if it were an alteration, in place, of former 
crystals and grains included in the carbonate. Some of the blue calcite 
also contains large individuals of this white material having sharply 



1917] Eakle: Minerals Associated with Crystalline Limestone 345 



defined crystal boundaries, apparently hexagonal in outline. No 
wilkeite occurs in it, but it is evidently an altered product, presum- 
ably from wilkeite. Analyses show that it is principally a hydrous 
calcium silicate with some of the silica replaced by the phosphate, 
sulphate and carbonate molecules. It is a new hydrous silicate of 
calcium having small amounts of the other oxides in place of the silica 
and the name crestmoreite, after the locality, is proposed for it. 

The mineral is compact snow-white with vitreous to dull lustre. 
H = 3. G = 2.22. It fuses quietly and easily to a slightly vesicular 
glass. It is very easily soluble in acid, leaving some flocculent silica, 
while most of the silica goes into solution. Some of the lime can be 
extracted by boiling water. 

The earthy opaque material is not adapted to good optical deter- 
minations. It has parallel extinction, positive elongation, low bire- 
fringence and /3 = 1.590 ± .005. 

Analyses of different samples of the mineral were made, all of them 
showing phospbates and sulphate in the substance. Some of the C0 2 
determined is due to calcite, which penetrates the mineral in thin seams 



SiO, 


36.12% 


38.30% 


34.42% 


CaO 


42.71 


41.20 


43.54 


P.O.-, 


2.38 


3.50 


3.50 


so 3 


2.42 


1.25 


2 24 


CO, 


1.16 






Ign. 


14.98 


15.17 


16.24 




99.77 


99.42 


99.94 



These analyses correspond approximately to the formula : 

20H,CaSiO, . Ca 3 (P0 4 ) 2 • CaS0 4 • CaC0 3 + 10ILO, 

and this requires the composition : 

SiO, 35.23% 
CaO 41.10 
P 2 5 4.17 
S0 3 2.35 
C0 2 1.29 
ELO 15.86 

If crestmoreite were a clear crystallized mineral like the wilkeite, 
ere would be no doubt that the phosphate, sulphate, and carbonate 
belonged to it and should be reckoned in its formula ; but its earthy 
structure and composition show that it is changing to a calcium 
silicate, and it is quite within reason to assume that the three acid 
radicals are small portions of those in the original wilkeite, which 



346 



University of California Publications in Geology [Vol. 10 



have not been entirely leached out, in the hydration and silication of 
the latter mineral, and therefore have no part in the formula for crest- 
moreite. An hydrous lime silicate is forming by the alteration of the 
wilkeite and the ratio of CaO : Si0 2 will be as 1 : 1 no matter how much 
water, or in what way, it enters into the composition. 

Crestmoreite can be represented by the simple formula CaSiO,-H 2 
which requires 

Si0 2 44.78% 
CaO 41.79 
H 2 13.43 

This would make it a simple hydrous metasilicate like a hydrous wol- 
lastonite, but it seems more probable that crestmoreite, from the water 
determinations and derivation from wilkeite, is a hydrous basic ortho- 
silicate. 

The following percentages of water were given off at the respective 
temperatures : 

At 102° 1.25% 
200 3.27 
300 10.27 
Bed heat 15.11 
Blast 16.76 

In view of the fact that most of the water is expelled only at the 
higher temperatures it can be regarded as constitutional, and the above 
formula can be written H 2 CaSi0 4 . 

Wilkeite is represented by the formula 3Ca 3 (P0 4 ) 2 • 3Ca 2 Si0 4 • 
3CaS0 4 • CaC0 3 • CaO, and it can readily be seen how the orthosilicate 
can increase at the expense of the more soluble phosphate and sulphate 
through the wilkeite alteration by carbonated and silicated waters. 
These waters were the heated ascending solutions which brought about 
some of the later crystallizations, and in the formation of the ortho- 
silicate part of the calcium was replaced by basic hydrogen. The 
exact formula for crestmoreite depends upon the water and therefore 
no formula can be advanced that is not open to criticism. As a basic 
silicate most of the water must be considered as constitutional. 

The formula proposed for crestmoreite is 4H 2 CaSi0 4 -|-2H 2 0. 
This requires : 

Si0 2 43.32% 

CaO 40.43 
Constitutional ILO 12.99 } 
Crystallization H 2 3.26 ^ 16-2 ° 



100.00 



1917] Eakle: Minerals Associated with Crystalline Limestone 347 

Biversideite, a New Mineral. — Some of the masses of vesuvianite 
contain narrow seams of a white fibrous mineral which has similar prop- 
erties to crestmoreite but with only half as much water, and it does 
not occur as an alteration of wilkeite, at least not as a direct alteration 
in situ. The mineral occurs in compact fibrous veinlets in the crevices 
of the massive vesuvianite and has a silky luster resembling satin spar. 
H = 3. G = 2.64. Fuses at 2 to a white glass. Easily soluble in 
dilute acid leaving flocculent silica. 

The mineral is a fibrous crystallization from the solutions carrying 
the altered wilkeite or crestmoreite and the analyses show that a lime 
silicate with a ratio CaO : Si0 2 equal to 1:1 is, like crestmoreite, the 
principal constituent with small amounts of the phosphate and sul- 
phate present. In this case also the P 2 3 and S0 3 are hardly to be 
considered as belonging to the mineral. 

Analyses of the fibers gave : 



Mean 



Si0 2 


41.29% 


41.22% 


41.26% 


CaO 


44.62 


44.55 


44.58 


P 2 5 




3.84 


3.84 


S0 3 


1.84 




1.84 


H 2 


8.05 


8.17 


8.11 



99.63 

The water determination gave 



At 102° 


0.80% 


150 


1.00 


250 


1.37 


Eecl heat 


7.77 


Blast 


8.05 



This water analysis would indicate that it is mainly constitutional, but 
it is a difficult matter to construct a basic formula for the mineral 
that is satisfactory. The simplest formula to express the composition 
of riversideite is 2CaSi0 3 -H 2 0. It may be likened to okenite with 
its basic hydrogen replaced by calcium : 

Okenite (H 2 Ca) Si 2 0„ . ILO 
Biversideite Ca 2 Si 2 0„ . ILO 

The formula 2CaSiO a • H„0 requires : 

Si0 2 48.00% 
CaO 44.80 
H 2 7.20 



348 University of California Publications in Geology [Vol. 10 



The analyses of riversideite correspond pretty closely to the formula 
15H 2 CaSi0 4 • 15CaSi0 3 • CaS0 4 • Ca 3 (P0 4 ) 2 + 5H 2 0, which requires: 



Si0 2 


42.00% 


CaO 


44.43 


S0 3 


1.87 




3.31 


H 2 


8.39 




100.00 



Disregarding the phosphate and sulphate it appears that the silicate 
formed is a combination of the basic orthosilicate and the metasilicate, 
and a formula to express the mineral may be written 6H 2 Ca 2 Si 2 0.-H 2 0. 
This requires : 

8i0 2 47.43% 

CaO 44.27 
Constitutional H.,0 7.111 
Crystallization fLO 1.19 

100.00 

The optical properties of riversideite kindly determined for the 
writer by Mr. E. S. Larsen are: 

a = 1.595 ± 0.003, Parallel extinction. 
y — 1.603 ± 0.003. Z parallel to fibers. 

The name riversideite, after the county in which it occurs, is proposed 
for this new hydrous lime silicate. 

The water content of a mineral is always subject to different inter- 
pretations; and it is not always possible to differentiate between 
hydroscopic, crystallization and constitutional water. Both of these 
new minerals might be interpreted as simple hydro-wollastonites. 

Crestmoreite CaSi0 3 ■ ELO 
Riversideite 2CaSi0 3 • H 2 

Clinochlore. — Small pale green flakes of elinoehlore were found in 
the vesuvianite-masses at the Commercial Rock quarry. 

Apatite. — Specimens of greenish blue apatite in granular form asso- 
ciated with green diopside and white wollastonite in white calcite were 
obtained from the quarry, but it does not appear to be an abundant 
mineral and no crystals of it have been collected. 

Aragonite. — Some of the lime carbonate has subsequently crystal- 
lized into the orthorhombic form. It occurs sparingly as fibrous and 
foliated thin layers interspersed with layers of quartz and calcite. 



1917] Eakle: Minerals Associated with Crystalline Limestone 349 



MINERALS ASSOCIATED WITH THE INTRUSIVES 

Feldspars. — Orthoclase, microcline, oligoclase, and labradorite are 
present in the quarries as constituents of the igneous rocks. Ortho- 
elase appears to predominate and it forms the larger part of the 
pegmatites. It occurs red and white. An analysis of the pure white 
from the pegmatites gave : 



Si0 2 


64.54% 


A1A, 


20.86 


Fe 2 3 


tr. 


CaO 


1.86 


MgO 


tr. 


Ign. 


0.52 


Na,0 


1.18 


K.,0 


11.85 




100.81 



G= 2.54 

Pyroxene. — Besides the good crystals of diopside which are scat- 
tered through the calcite, there is a deep green pyroxene resembling 
omphacite, mixed with cinnamon-garnet, which has formed at the 
contact of the pegmatite and limestone. 

Augite. — Occurs as a constituent of the quartz-monzonite porphyry. 

Hornblende and Biotite. — Both of these minerals are constituents 
of the granodiorite, the hornblende greatly predominating. Neither 
seems to occur in the monzonite or pegmatite. 

Titanite. — Granular titanite is rather abundant in the monzonite 
as a constituent. It occurs pale brown with a marked pleochroism to 
deeper brown. None of the grains has a crystal boundary. 

Zircon. — Minute crystals and larger grains of zircon are scattered 
through some of the white pegmatite rock. The color of the mineral is 
clove-brown and some of the crystals show the forms (100), (110), 
(111), (331). 

Epidote. — Deep green epidote occurs as one of the contact min- 
erals of the Commercial Rock quarry. Slender and long crystals and 
grains are imbedded in some of calcite masses. The mineral is very 
prominent as a constituent of the pegmatites and is one of the original 
minerals of the rock. It is present in the pegmatite as long slender 
crystals having a prominent basal cleavage. The fresh crystals are 
deep leek-green, but most of them have altered to a bronze-brown and 
resemble astrophyllite. The elongation of the crystals is parallel to 



350 University of California Publications in Geology [Vol. 10 



the &-axis as usual, and they show striated domes with the cleavage 
base, but no end-faces. 

Quartz. — Specimens of compact granular quartz rock found in the 
talus of the Commercial Rock quarry indicate that seams of quartzite 
were formed in the crystallized limestone by its metamorphism. It is 
quite possible that sandstone seams occurred in the original formation 
and that these have been the source of much of the silica necessary to 
form such an abundance of silicate minerals. Quartz is a minor con- 
stituent of the igneous rocks and occurs in the usual smoky-brown 
color. Small druses of the mineral are occasionally found, but large 
crystals are rare. 

Tourmaline. — Boron is a characteristic element in the rocks of 
Southern California and practically all of the pegmatites of that 
region carry boro-silicates, especially tourmaline. Three of these boro- 
silicates have been observed in the pegmatites of Sky Blue Hill and 
a few specimens have been collected, but the writer is without any 
data concerning them. 

The tourmaline is black columnar and occurs sporadic in the 
pegmatite. 

Axinite. — Violet-colored axinite associated with cinnamon-garnet 
occurs in large fragments in the pegmatite. Bright crystal faces, often 
striated, occur but crystals are not complete enough to measure. 
Axinite appears to be common in this particular region, as it is 
abundant at the Riverside quarry and has been noted in other places 
in the vicinity. Rogers 8 has described a large crystal from Riverside. 

Datolite. — Glassy white datolite with slightly greenish tinge occurs 
in connection with the pegmatites. The specimens sent to the writer 
are compact massive. 

Seapolite. — Specimens of seapolite were recently collected by 
Chilcls. The mineral is in close association with green pyroxene, 
quartz, feldspar, wollastonite, and grossularite garnet. The color of 
the seapolite is grayish white, but it contains violet-blue streaks. The 
variety is probably wernerite. 

Apophyllite. — The masses of wollastonite which have formed on the 
contact between the pegmatites and limestone contain cavities lined 
with small crystals of apophyllite. The crystals are colorless to white 
and are usually closely interlocked. Two habits are prominent; one 
is the common cubo-octahedral type with small faces of the pyramid 
and the base and second-order prism about equal in size. The other 

s School of Mines Quar., vol. 33, p. 373, 1912. 



1917] Eaklc: Minerals Associated with Crystalline Limestone 



351 



one is the pyramid type with a very small or no base. Only the three 
forms (001), (100), and (111) occur on the crystals. Some of the 
crystals have been corroded by solutions and altered into white fibrous 
okenite. 

Okenite. — Radiating botryoidal coatings of okenite occur on the 
apophyllite evidently as an alteration product. The coatings consist 
of tufts of fibers and long slender needles. The acicular crystals are 
too slender for accurate measurements but they appear to be long 
prisms terminated on their ends by dull domes. Some approximate 
measurements and an analysis of the mineral were made by William 
Foshag. 

Measured 
(110):(1T0) 33°40' 

(010) :(011) 52 00 

(011) : (Oil) 75 00 

The analysis gave : 

Calculated for okenite 
H 2 Ca(Si0 3 ) 2 .H 2 

Si0 2 56.17% 56.60% 

CaO 26.10 26.42 

H 2 16.83 16.98 

99.10 100.00 

The crystals have parallel extinction and are probably orthorhombic. 
H = 4-4.5. G = 2.206. Index of refraction = 1.55. Low birefring- 
ence, 0.008-0.009. Solution in HC1 yielding flaky silica. Fuses easily 
and gives water in a closed tube. It has formed from apophyllite 
through the action of carbonated waters, perhaps according to the 
equation : 

2H,KCa 4 (Si0 3 ) 8 + H 2 C0 3 = 8H 2 Ca(Si0 3 ), + K 2 C0 3 . 

Prehnite. — Two distinct varieties occur filling cavities in the white 
feldspar of the pegmatite. The first is the common green drusy 
prehnite. This is intimately associated with laumontite, which may be 
secondary from it. The second variety is unusual for prehnite. It is 
light brown to colorless and lacks the drusy surface. In some of the 
cavities crystals line the walls, but they are so interlocked that single 
crystals are not separable. One crystal about five millimeters broad 
and one millimeter thick showed the forms c (001), m (110), a (100), 
and o (061). The base is large and bright but the edge-faces are dull. 
Most of this brown variety is compact granular with bright basal 
cleavage planes prominent. It is associated with massive datolite and 
gray quartz. 



352 University of California Publications in Geology [Vol. 10 



An analysis of this brown variety gave : 

Si0 2 44.10% 

A1 2 3 24.20 

CaO 25.20 
H 2 5.86 

99.36 

Laumontite. — The green prehnite has laumontite coating it in small 
divergent columnar and fibrous masses. It has the appearance of a 
secondary alteration of the prehnite and in all probability it is such, 
although there is no direct evidence to prove it. The mineral is snow- 
white with vitreous luster. Some of the stouter needles have the 
characteristic oblique cleavage ends. It fuses readily to a vesicular 
glass and is easily and completely soluble in HC1, yielding a thick 
gelatinous mass. 

An analysis gave : 

Si0 2 53.49% 
A1,0 3 22.01 
CaO 10.80 
MgO tr. 
H 2 13.39 

99.69 

Opal. — White hyalite coats the walls of some of the cavities in the 
feldspathic pegmatite, and it coats the apophyllite and okenite to some 
extent. Under the electric spark it shows strong yellow luminescence, 
which is an indication that it contains uranium. The amount of 
material on hand is too small to determine the uranium chemically. 

Besides this hyalite opal there is considerable wood opal in some 
portions of Sky Blue Hill. It is dark brown and black, becoming gray 
by heating. It shows the wood structure and some of it has small 
calcite rhombohedrons deposited on it. 

SULPHIDE MINEEALS 

Arsenopyrite, pyrite, galena, sphalerite, greenockite, bornite, 
chalcopyrite, and tetrahedrite occur in the Commercial Kock quarry, 
mostly in association with the pegmatite intrusives. 

Arsenopyrite has been found in a few small crystals about two 
millimeters long. 

Pyrite is more disseminated than the other sulphides. It occurs in 
grains, cubes and pyritohedrons, and much of it is altered into brown 
limonite pseudomorphs. 



1917] Eakle: Minerals Associated with Crystalline Limestone 353 



Galena occurs in rather large cubes and also massive granular. 
The specimens collected are associated with garnet dodecahedrons, 
quartz, sphalerite, pyrite, and chalcopyrite. 

Sphalerite is quite black but has the characteristic resinous luster 
and good cleavage. It occurs in the vesuvianite-garnet masses and 
some of it contains small coatings of bright yellow greenockite. 

The copper minerals, bornite, chalcopyrite, tetrahedrite, and per- 
haps chalcocite, have been found in grains and small granular masses 
in the metamorphic zones of silicates. 

OXYDATION PEODUCTS 

Azurite and malachite occur as thin coatings and as stains in the 
vesuvianite-garnet mass of rock. Cerussite and anglesite have both 
been identified as earthy gray coatings on the galena. 

The two oxides of iron, limonite and hematite, are common in small 
earthy masses and as stains. The weathered brucite limestone of the 
Commercial Rock quarry has much yellow earthy limonite and deep 
red hematite filling the cellular cavities left by the leached-out brucite. 
The crystals and grains of pyrite imbedded in the calcite and even 
in the pyroxene and other silicates have been largely altered into 
limonite pseudomorphs, probably readily changed by the action of the 
carbonated waters. 

White clay from the orthoclase and chlorite from the epidote, 
augite, hornblende, and other silicates are natural alteration products. 



PLATE 21 

View looking northeast, showing the two hills and the cement plant of the 
Riverside Portland Cement Company at Crestmore, Riverside County, California. 
The quarry floor marks the juncture of the limestone and granodiorite. 



[354] 



PLATE 22 

Three views showing different portions of the commercial rock quarry on the 
eastern side of Sky Blue Hill. The quarry face and boulders are mostly mixtures 
of blue and white calcite, brown vesuvianite and garnet and green diopside. 



[356] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL. 



[EAKLE] VOL. 10, PL. 22 




PLATE 23 

Projections of wollastonite crystals, showing the different types and com- 
binations of forms. Figure 1 is the type most common for wollastonite. Figures 
2 and 3 are types common at Crestmore. The left half of figure 3 is the rear 
of the right half drawn to show a center of symmetry only, if the crystal were 
doubly terminated. Figures 4 and 5 are orthographic projections of the ends, 
showing better the front and rear faces and the absence of an axis of symmetry. 



[358] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL. 



[EAKLE] VOL. 10, PL. 23 




PLATE 24 

Figures 6-8 are projections of vesuvianite crystals showing the general type, 
but different combinations of forms. Figures 9 and 10 are diopside, showing the 
characteristic type and combinations. 



[360] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL 



[EAKLE] VOL. 10, PL. 24 




UNIVERSITY OF CALIFORNIA PUBLICATIONS 

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Vol. 10, No. 20, pp. 36 1 -382, pis. 25-27, 3 text-figures November 8, 1917 



THE GEOLOGY AND ORE DEPOSITS OF 
THE LEONA RHYOLITE 



CLIFTON W. CLARK 




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UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

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Vol. 10, No. 20, pp. 361-382, pis. 25-27, 3 text-figures November 8, 1917 



THE GEOLOGY AND ORE DEPOSITS OF THE 
LEONA RHYOLITE 

BY 

CLIFTON W. CLARK 



CONTENTS 

PAGE 

Character and Purpose of the Work 362 

Physical Features of the Area 362 

Pre-Reeent Erosional Surface 363 

Geological History 364 

Distribution of the Rhyolite 365 

Nature of Surface upon which Lava Flowed 365 

Age of the Rhyolite 366 

Faulting 366 

General Features of the Rhyolite 367 

Petrographical Characters 368 

Felsite Faeies .„. 368 

Felsophyric Facies '. 369 

Vitrophyric Facies 369 

Microlitie Facies 369 

Distribution of the Different Faeies — 370 

Summary of the Microscopic Study 371 

Chemical Characters 371 

Pyrite Deposit - - 372 

Location - 372 

Underground Development 373 

Occurrence 373 

Mineralogy - 374 

Metallographic Study of the Ore 374 

Genesis of the Ore 375 

The Relation of Fracturing to the Ore Deposit 377 

The Reducing Effect of the Rhyolite _ 377 

Summary 37 



362 University of California Publications in Geology [Vol- 10 



CHAEACTER AND PURPOSE OP THE WORK 

During the fall of 1915 and part of the winter of the year 1916 
the writer spent considerable time in the study of the Leona rhyolite 
as to its extent, its petrographical character, the nature of the surface 
on which it rests, its structural features, its age and the ore deposits 
in it. 

Professor A. C. Lawson 1 in the San Francisco Polio has given a 
brief account of the rhyolite and its relations and mapped its distri- 
bution. He also devotes a paragraph to the description of the ore 
deposits. It is the purpose of this paper to give a more detailed 
description of this very interesting feature of Coast Range geology. 2 

PHYSICAL FEATURES OP THE AREA 

The area occupied by the Leona rhyolite is confined to a portion 
of the front of the Berkeley Hills, which form the steep northeast 
boundary of the valley of San Francisco Bay. The cities of Berkeley 
and Oakland are in part located on the foothill slopes, but for the most 
part they are situated on the alluvial embankments, in part terraced, 
at the base of the hills. These embankments are now being dissected 
by the streams which formed them. The front of the hills has a 
straight northwest-southeast trend and is continuous in its abrupt 
elevation above the bay plain from San Pablo to the town of Hay- 
wards, except for a few canons which dissect it. A remarkable break, 
however, occurs at Haywards, where Castro Valley forms a flask- 
shaped einbayment connecting by a narrow gap with the Valley of 
San Francisco Bay. 

The rhyolite, being more resistant to erosion than the surrounding 
formations, stands out in relief along the front of the hills from its 
northern end at Berkeley to the vicinity of Haywards. But south 
of this point it is less prominent and conforms more to the aspect of 
the topography of the adjacent rocks. The rhyolite is everywhere 
studded with crystals of pyrite, the oxidation of which has given the 
characteristic reddish color to the formation. In certain sections 
where the outcrop of the rhyolite is obscure, the color of the soil 
derived from it was of material aid in determining its boundary. 

i U. S. GeoL Surv., San Francisco Folio, no. 193, 1914. 

- The writer wishes to express his thanks to Professor A. C. Lawson for 
helpful suggestions and criticism in the preparation of this report, and also to 
Mr. D. A. McDonell, General Manager of the Leona Chemical Mine, and to Mr. 
J. M. Conlin, Mine Superintendent, for many courtesies extended during the 
examination, of the mine. 



1917] Clark: Geology and Ore Deposits of the Lcona Rhyolite 363 



Pre-Recent Erosional Surface. — In the vicinity of Blmhurst there 
is evidence of an old erosional surface whose remnants form part of 
the present topographical surface. The general direction and possible 
extent of the stream which flowed on this surface is shown by the 
sketch map in figure 1. It is not known how extensive this former 
surface may have been, but the evidence used in making the map 
consists of the presence of stream pebbles composed mostly of Oakland 
conglomerate and boulders of Chico sandstone. The pebbles found 
lying loose upon the surface are probably the last trace of the former 
stream deposits. The small area north of Lake Chabot, mapped as 
Knoxville, is partially occupied by these pebbles imbedded in alluvium 




Fig. 1. Sketch, in part, hypothetically drawn, showing the pre-recent stream 
system and its relation to the present topography. The dotted lines represent 
the pre-recent stream valleys. The branching full lines represent the present 
streams. The heavy lines represent faults. 

derived from the formations to the east. North of the F. C. Talbot 
ranch about a mile, along the road leading to the country club, there 
is a considerable thickness of the old river gravels. Here cross- 
bedding is well exposed on both' sides of the former stream valley. 
To the south of the road just referred to, in an old stone quarry, the 
stream gravels are exposed in vertical section. The deposit is about ten 
feet thick and rests on an uneven eroded surface of the rhyolite. This 
old stream valley has a course transverse to the present streams. The 
presence of pebbles on the tops of some of the hills indicates that the 
former stream system antedates that of the present by a considerable 
period of geologic time. 

The direction of the present stream valleys being at such variance 
with those of the pre-Eecent indicates that the former were superim- 



364 University of California Publications in Geology [Vol. 10 



posed upon the latter. A considerable portion of the country just 
east of the Haywards fault was covered with detritus and then 
elevated, the uplift giving rise to the present stream system. 

As near as can be judged, at least a branch of the old stream flowed 
out through Arroyo Viejo Creek during the last stages of its existence. 
There must have been a large amount of detrital material deposited 
on the lower hillslopes at the advent of the present erosional cycle. 
This material has been largely if not all covered by recent alluvium. 
The former stream system probably represents the period in which 
the San Antonio formation was deposited. Material similar to that 
in the San Antonio formation covers a considerable area of the Knox- 
ville just north of Lake Chabot. The material here, however, contains 
many large boulders, which at some places are imbedded in the finer 
alluvium ; it is the finer alluvium that is similar to the San Antonio. 

GEOLOGICAL HISTOEY 

The portion of the Berkeley Hills here considered is composed of 
several kinds of rocks, both igneous and sedimentary. The oldest of 
these, comprising sandstone, conglomerate, quartzite, radiolarian chert, 
serpentenized peridotite, diabase, ellipsoidal basalt, and glaucophane 
schist, compose the Franciscan group. 3 Upon this group the lower 
Cretaceous or Knoxville formation rests unconformably. It is pre- 
vailingly a fine-grained arenaceous and carbonaceous shale having a 
thickness of several hundred feet. As has been pointed out, 4 the shale 
contains no coarse sand or conglomerate at its base, which would signify 
a slowly transgressing sea. The lack of this coarse material would seem 
to indicate that the surface of the Franciscan must have been reduced 
to low relief and submerged rapidly. 

Upon the Knoxville shale rests the Chico or upper Cretaceous. 
The Oakland conglomerate at the base of the Chico ranges in thickness 
from 100 feet near Temescal Lake to perhaps 800 or 900 feet east of 
Leona Heights ; near Lake Chabot it reaches a thickness of 1000 to 
1200 feet; but it is probably not thicker than 1000 feet near the 
southern end of the Haywards quadrangle. The upper portion of the 
Chico is composed of sandstone and shale many thousand feet thick. 

The apparent conformity of the Oakland conglomerate and the 
Knoxville is an interesting point connected with the geologic history 

s Op. tit., p. 4. 
* Op. tit., p. 8. 



1917] Clark: Geology and Ore Deposits of the Leona Rhyolite 365 



of the region which is discussed in the text of the San Francisco Folio. 
The pebbles of the conglomerate are mostly chert, shale, and sandstone, 
but along with these are numerous boulders of granite and grano- 
diorite. It seems, therefore, that there must have been marked dia- 
strophic movements at the close of the Knoxville epoch, but these 
movements were not of such a nature as to raise the Knoxville sedi- 
ments above sea-level. 

After erosion which locally removed the Shasta-Chico rocks, the 
Leona rhyolite was extruded on the surface as a lava flow. From its 
present disposition it appears that the flow probably followed an ero- 
sional valley. The valley must have roughly followed the contact of 
the Knoxville and the Franciscan. Since the extrusion of the rhyolite 
there have been several crustal movements. 5 These movements have 
continued up to recent geologic time, as is shown by the various alluvial 
deposits, and also by the present streams that in many instances show 
recent readjustment. The most recent movement has been faulting 
along a line generally parallel to the Berkeley Hills. 

DISTRIBUTION OF THE RHYOLITE 

The rhyolite forms a narrow discontinuous belt that extends from 
Hamilton gulch at Berkeley to a point about five miles southeast of 
the town of Hay wards, a total length of about twenty-two miles. The 
lava flow has a maximum residual thickness of about 400 to 600 feet, 
but generally it is much thinner. It presents a rather distinct physio- 
graphic feature on the front of the hills due to the steep slopes of its 
erosional forms. At a number of localities the streams have eroded 
through the entire thickness of the rhyolite and are now cutting into 
the older rocks below. Indeed, it seems quite evident that the dis- 
continuous areas of rhyolite are remnants of a former continuous lava 
flow that was much thicker and wider. 

NATURE OF SURFACE UPON WHICH LAVA FLOWED 

In some places the rhyolite rests upon the Franciscan, in others 
upon isolated patches of Knoxville which were not entirely removed 
from the Franciscan by erosion at the time of its extrusion, so that the 
lava probably occupied the valley into which it flowed. It was hoped 
that considerable quantities of stream gravel would be found below 

o Op. ext., p. 20. 



366 University of California Publications in Geology [Vol. 10 

the rhyolite, but in two or three places only were any gravels found 
in such a position, and in these places in very limited amounts. How- 
ever, this does not preclude the possibility that they underlie the 
rhyolite, because in only a few places is the base of the rhyolite clearly 
exposed. 

The field relations and petrographical character of the rhyolite, 
which will be discussed later, indicate that the lava probably came 
from one source and was extruded as a single flow. 

AGE OF EHYOLITE 

The age of the rhyolite is one of the principal points to be consid- 
ered, but after much detailed study of its relation to the adjoining 
formations the time of extrusion has not been narrowly determined. 
It is certainly post-Chico, and, judging from the degradation of the 
surface upon which the rhyolite rests, the degree of its alteration, the 
amount of its erosion, and the extent of post-rhyolite movements, 
it seems highly probable that it is as old as Pliocene, as has been 
suggested. 6 

FAULTING 

The Berkeley Hills orogenie block 7 is a feature of especial interest 
in the geology of the Coast Eanges in the San Francisco Bay region. 
The Haywards fault, which traverses this region nearly parallel to 
the trend of the rhyolite belt, is comparable to the San Andreas fault 
because of the similar geomorphic features it has produced. It ex- 
tends through the area mapped, from Berkeley southeast along the 
base of the steep slope to the vicinity of Temescal Lake, where it be- 
comes manifest as a rift valley to a point southeast of Leona Heights ; 
here it turns in a more southerly direction and passes through the 
low front ridge of the hills out under the alluvium. At Arroyo Viejo 
Creek the rift again returns to the rhyolite area and passing up this 
creek in a southeasterly direction through a well defined saddle on 
the F. C. Talbot ranch connects with the oblique fault west of Lake 
Chabot. The main fault may be offset somewhat by this oblique fault, 
but from this point it has been tentatively drawn on the map through 
the several saddles and breaks in the western slope of the hills to the 
town of Haywards, where it is lost as it passes out under the alluvium. 

e Op. ext., p. 12. 
i Op. cit., p. 17. 



1917 ] Clark: Geology and Ore Deposits of the Leona Rhyolite 367 

Numerous faults of smaller dimensions and probably intimately associ- 
ated with the Haywards fault have been observed in the area. These 
minor faults are oblique, parallel, and transverse to the Haywards 
fault. The northern exposure of rhyolite is cut off at Hamilton gulch 
by a fault that is transverse to the major movement. This portion of 
the rhyolite is also faulted against the Chico and Knoxville formations 
along most of its eastern boundary. At Leona Heights two faults 
more or less parallel to the Haywards fault and undetermined in 
extent have aided in producing the geomorphic features of this locality. 
South of Lake Chabot and again south of Haywards oblique faults 
extend in a southeasterly direction from the main fault. These ob- 
lique faults are probably connected with a main fault, approximately 
parallel to the Haywards fault, that traverses the country from 
Lake Chabot southeasterly. 

In general the relative movement along the fault plane appears to 
have been horizontal rather than vertical. At Temescal Lake quite 
extensive masses of gouge and breccia are exposed at the surface in a 
railroad cut that traverses the fault for a short distance. It does not 
seem likely that this amount of gouge was produced by any vertical 
movement that could have taken place here. It is quite certain that 
a considerable movement has occurred along the Haywards fault in 
recent geological time, as is evidenced by the diversion in the direction 
of the streams that flow transverse to the fault valley. Any statement 
as to what effect the faulting has had in the geomorphogeny of the 
region, the number of movements and the geologic epoch in which they 
occurred would be largely conjectural. But there probably have been 
several periods of movement along this fault zone in post-rhyolite time, 
and there is a possibility that the rhyolite may have been extruded at 
some point on the zone. 



GENERAL FEATURES OF THE RHYOLITE 

The Leona rhyolite reaches its maximum width of one and one-half 
miles a little north of the F. C. Talbot ranch, east of Elmhurst. The 
lava varies in thickness, but reaches a maximum of perhaps 600 feet. 
Where fresh the rhyolite is light green to bluish in color and varies 
in texture, being glassy and porphyritic in the northern part, while 
towards the southern end it is less porphyritic and becomes more 
felsitie. The rhyolite is everywhere studded with pyrite crystals and 
contains very few ferromagnesian minerals in the fresh rock. Certain 



368 University of California Publications in Geology [Vol. 10 

facies show amygdaloidal structure, but flow structure is not common, 
except in certain glassy facies. It is everywhere jointed and frac- 
tured and under weathering processes yields a soil which contains 
numerous angular fragments. The chemical alteration of the pyrite 
has produced iron oxide that stains the soil to a characteristic brown 
or red color, so that the regolith of the lava is readily recognized in 
the field. 

PETROGRAPHICAL CHARACTERS 

The Leona rhyolite may be divided into four facies, according to 
texture. The first, which shows the most advanced degree of crystal- 
lization, has a felsitic texture and is composed of quartz and feldspar, 
which only rarely attain phenoerystic development. This will be 
known as the felsite facies. 

The second facies is similar to the above, but consists of pheno- 
crysts of feldspar and quartz set in a dense groundmass that in places 
is microcryptocrystalline, but is generally cryptocrystalline. This will 
be designated the felsophyric facies. 

The third facies is characterized by well developed quartz and acid 
plagioclase phenocrysts set in a glassy ground mass and will be desig- 
nated the vitrophyric facies. 

The fourth, or microlitic facies, may well be divided into two 
varieties, one the glassy and the other the spherulitic. The glassy 
variety has a hypocrystalline ground mass which grades into a dense 
glass. The crystalline constituents of the ground mass are mostly 
quartz, but minute needles of feldspar are sparingly included in the 
matrix. The spherulitic variety has a glassy ground mass which shows 
radiolitic areas as distinct from the more dense glass. This grades 
into devitrified areas which show a cryptocrystalline character. The 
spherulites are sporadically distributed through the matrix, and also 
occur sparingly embedded in the phenocrysts. 

Felsite Facies. — This is a brownish white rock, composed of feld- 
spar and quartz, having a subconchoidal fracture and a felsitic texture. 
A very few phenocrysts of oligoclase are present in the ground mass, 
which is cryptocrystalline and altered. The quartz crystals are fre- 
quently rounded by corrosion, but in spots secondary quartz is present 
in quite large aggregates along fractures. The accessory minerals are 
pyrite, magnetite, leucoxene, and small needles of apatite. 



1917] Clark: Geology and Ore Deposits of the Leona Rhyolite 369 



FelsopJi yric Fades. — This is a light green to brown rock contain- 
ing numerous dense, cloudy, indistinct patches. It has a subcon- 
choidal fracture very similar to that of the rock just described. The 
ground mass is composed of feldspar and quartz in various irregular 
aggregates. The white clouded patches appear to be composed of 
alteration products which are not determinable. In the finer part of 
the matrix chlorite is present, producing a bluish-green stain in the 
altered products. The phenocrysts are mostly plagioclase, but a few 
aggregates of orthoclase and quartz occur in the matrix. The acces- 
sory minerals are pyrite, magnetite, zircon, and apatite. 

Vitrophyric Fades. — This is a light blue to gray rock having a 
cryptocrystalline ground mass which appears under the microscope to 
grade into a hypocrystalline aggregate. Numerous crystals of feld- 
spar, together with some quartz and irregular masses of magnetite, 
constitute the phenocrysts. A few flakes of biotite partially altered 
to chlorite are also present in the rock. The small aggregates which 
make up the matrix are of two kinds : one is principally composed of 
rounded grains with rare elongated forms, while in the other the 
elongated crystals of feldspar and quartz form most of the ground- 
mass and the few rounded grains present have been derived mostly 
by alteration and addition of secondary quartz. The phenocrysts are 
mostly oligoclase feldspar and quartz, with a few poorly developed 
crystals of orthoclase. Some of the feldspar phenocrysts have been 
partially silicified, so that they appear as a dense brownish colored 
mass that does not always show the original crystalline structure. The 
accessory minerals are pyrite, magnetite, apatite, and zircon. 

Microlitic Facies. — The microlitic facies is composed of two varie- 
ties of glassy rock. 

1. The first has a cryptocrystalline ground mass which grades into 
an undeterminable, brownish glass studded with minute elongated feld- 
spars and grains of quartz. In portions of the rock these elongated 
needles of feldspar are oriented in a single direction, giving rise to a 
flow structure which is common in this facies of the rhyolite. Feld- 
spar forms the most important phenocrysts, if we exclude certain 
quite large aggregates of quartz and irregular masses of magnetite 
in the matrix. Most of the feldspar is altered to kaolin and silica, 
which form dense clay masses colored dark blue by chlorite. Certain 
portions of the rock frequently show an intermediate stage between 
the dense glassy base and the microlitic structure. 



370 University of California Publications in Geology [Vol. 10 



2. The second variety is of a light gray, green or bluish color, 
except where stained with iron oxide ; it has a subconchoidal fracture, 
appears massive, and is very hard. Under the microscope the ground 
mass appears to be cryptocrystalline or microlitic, and in it are scat- 
tered numerous groups or aggregates of spherulites, which are of two 
kinds : those that are in circular groups imbedded in a dense brown 
glass, and those that are sporadically scattered through the ground 
mass, and are also present in the altered phenocrysts. The former are 
microscopic in size, spherical in shape and show no distinct radiating 
fibers, but give a black cross between the crossed nicols, as shown in 
plate 25, figure A. According to Iddings, 8 the number of plates of 
feldspar composing such spherulites increases to such an extent that 
the outline of each individual plate is lost ; and when no distinct trace 
of any single fiber can be seen the ideal spherulite is produced. The 
second kind of spherulite is composed of fibers and plates, whose out- 
lines can be seen under the microscope. In some cases they appear 
to radiate from a small grain at the center, probably quartz. These 
spherulites do not show a black cross between the crossed nicols. They 
appear to be as numerous in the altered phenocrysts as in the glassy 
matrix. According to Iddings, spherulites of this type are composed 
of radiating plates or prismoid crystals. An example is shown in plate 
25, figure B. This variety of the microlitic facies does not show the 
flow lines as distinctly as that first described, but both kinds of spheru- 
lites are present in most of the sections examined of this facies. 



DISTRIBUTION OF THE DIFFERENT FACIES 

The four types of rhyolite have a rather definite distribution along 
the extent of the outcrop. The rock grades from a more glassy facies 
at the northern end of the belt to a more crystalline facies at the south- 
ern end. Both varieties of the glassy facies were obtained in that por- 
tion of the belt between Berkeley and Leona Heights. At Leona 
Heights some of the specimens collected were glassy, while others 
showed a distinct porphyritic character. From the vicinity of Leona 
Heights to Lake Chabot the rock is predominately porphyritic in text- 
ure. South of Lake Chabot to the town of Haywards the felsophyric 
facies predominates; that is, the ground mass in the rhyolite becomes 
much more granular and the glassy material is not so common in the 

s Iddings, J. P., Igneous Rocks, vol. 1, p. 229, 1909. 
9 Op. cit., p. 229. 



1917] Clark: Geology and Ore Deposits of the Lcona Rhyolite 371 



matrix. In this facies the phenocrysts are much less common, and 
those present are of small dimension. The rhyolite southeast of 
Haywards has been classed as felsite. In this portion of the outcrop 
alteration has been so intense that fresh rock is very hard to obtain. 
However, the rock shows a rather uniform felsitic texture, with a 
feeble development of small phenocrysts. 

SUMMAKY OF THE MICEOSCOPIC STUDY 

The petrographical study of the rhyolite shows that it may be 
divided into four facies largely based upon textural differences. The 
series includes a range of facies from those which are mostly glassy 
to those which are holocrystalline containing only a few small pheno- 
crysts. 

The rock is comparatively simple and rather uniform in compo- 
sition. Orthoclase, plagioclase, mostly oligoclase, and quartz are the 
essential constituents of the original rock. The accessory minerals 
are pyrite, magnetite, apatite, zircon, and leucoxene. Only the first 
three mentioned are in abundance. This study seems to support field 
evidence that the different facies are probably products of a single 
lava flow and came from a common source. 

CHEMICAL CHARACTERS 

The chemical composition as given in three different analyses is as 
follows : 10 

(1) (2) (3) 

SiO, 71.00 72.12 71.60 

Ti0 2 17 .12 

ALO, 12.70 11.49 11.93 

Fe,0 3 66 2.77 3.00 

Feb 2.44 2.30 3.40 

MnO 10 .09 

CaO 90 .94 .52 

BaO Trace 

MgO 1.39 .85 1.33 

Na.,0 6.45 5.28 4.62 

K.,6 2.99 .86 1.90 

P~0 5 88 .62 

SO. .08 

CO, 1.15 .38 

IYS. 03 

CI Trace 

H,0 (at 110° C.) 28 .06 .07 

Ignition 1.56 .96 .55 

100.37 99.96 100.21 

(1) Analyzed by C. P. Richmond in the laboratory at the University of California. 

(2) and (3) Analyzed by G. E. Colby in the laboratory at the University of California. 

10 U. S. Geol. Survey., San Francisco Folio, no. 193, p. 12, 1914. 



372 University of California Publications in Geology [Vol. 10 



The analyses cannot be considered to represent the composition of 
the original rock, for all of the specimens collected have suffered 
partial alteration. The high content of silica and low percentage of 
lime, with a rather high content of Na to that of K, indicates that the 
rock is a soda rhyolite. The rather constant percentage of A1,0 3 in 
the three analyses given above is of interest because in all the sections 
studied of this rock free kaolin was observed as an alteration product. 




Fig. 2. Plan of mine workings. 



PYRITE DEPOSIT 

Location. — Near Leona Heights, east of Oakland, deposits of pyrite 
occur in the rhyolite which have been mined for a number of years. 
At the present time two mines are in operation, one having just re- 
cently started. One of these mines, once known as the Leona Heights 
Mine, was described in 1911. 11 The larger mine, operated by the 
Leona Chemical Company, is the principal source of information con- 
tained in this report. 

ii Mace, Clement H., Min. and Eng. World, vol. 35, p. 1320, 1911. 



1917] Clark: Geology and Ore Deposits of the Leona Rhyolite 373 



Underground Development. — The mine of the Leoua Chemical 
Company is opened by two tunnels entering the hill at two levels, 
75 feet apart. The approximate position of the tunnels and of the 
ore body is shown in figures 2 and 3. The ore observed in the workings 
is in a potato-shaped mass in the mineralized zone, and is of two kinds. 
The soft ore is nearly everywhere surrounded by gouge ranging from 
a few inches to two or three feet in thickness. The hard ore, which 
forms but a small part of the deposit, is highly silicified, contains more 
chalcopyrite, and is not bounded by fault gouge. 

Most of the ore has been taken from the lower level, although quite 
important bodies extend above the upper tunnel. A winze was put 
down 40 feet from the north crosscut on the lower level, and it is said 




Fig. 3. Diagrammatic vertical section of ore body along line A-A'. 



that ore was encountered all the way down. A raise was driven from 
the southeast part of the lower tunnel and ore was struck 20 feet above 
the level, so that it is evident that the ore body dips into the hill, as 
is shown in the vertical section. 

Occurrence. — The ore is confined to the rhyolite and is not in 
contact with any other rocks so far as is known, but the deposit 
described by Mace 12 rests on a shale, probably Knoxville, and not a 
part of the Franciscan, as he suggests. The pyrite is massive and has 
fragments of country rock included in it. The ore occurs in a fracture 
zone in the rhyolite, which is jointed and faulted so that considerable 
quantities of gouge and small displacements may be seen nearly every- 
where in the mine ; but there is abundant evidence of more intense 
fracturing and differential movement that has probably caused the 
localization of the ore bodies. 

At nearly every place in the mine where the margin of the ore is 

is op. ext., p. 1320. 



374 University of California Publications in Geology [Vol- 10 

exposed the latter is surrounded by a considerable thickness of gouge 
composed mostly of kaolin and silica partly replaced by pyrite, an 
illustration of which is shown in plate 26, figure A. The pyrite com- 
monly grades out from the solid ore through the gouge into the wall 
rock. In some of the most recent workings a hard type of pyrite has 
been encountered. Although a small mass of this was struck on the 
lower level, yet the main body was encountered in a raise from this 
level. This ore contains a considerable quantity of chalcopyrite. The 
wall rock adjacent to the ore, and into which it grades, is highly silici- 
fied and contains small masses of kaolin. It is more thoroughly crystal- 
line, contains a larger percentage of silica, and is much harder than 
the other type of pyrite. An illustration of this is shown in plate 26, 
figure B. 

Mineralogy. — The minerals derived from the ore according to 
Schaller 33 are pyrite, chalcopyrite, copper, melanterite, pisanite, chal- 
canthite, copiapite, epsomite, hematite, limonite, alunogen (?) and 
boothite. Besides these the writer has observed chalcocite, bornite, 
and sphalerite in the ore. The pyrite, however, is the only mineral 
of economic importance and is used to make sulphuric acid. 

Metallographic Study of the Ore. — -A number of polished surfaces 
of the pyrite and of the country rock partially altered to pyrite were 
studied for the purpose of determining the nature of the metasomatic 
replacement of the rock by the pyrite and associated sulphides. The 
two types of pyrite already described show a rather marked difference 
under the metallographic microscope. The crystals of pyrite in the 
massive or softer ore are not so well cemented together as are the 
crystals in the harder type, but appear to be more dense and do not 
contain as much silica. The mineral has a very irregular pitted 
surface even after careful polishing, and the whole mass is made up 
of materials varying in density and hardness and also in the degree 
of cementation of their constituent parts; consequently no good pol- 
ished surfaces were obtained. Quite often the outlines of large cubes 
can be seen, but the pyrite constituting these is in very small crystals 
and may often be picked out with a needle point. Between these large 
cubical or irregular masses are distributed smaller patches of pyrite, 
which are generally hard and can be polished. The remaining area 
is mostly occupied by very small crystals of pyrite mixed with dark 
silica. It is very probable that this portion of the ore is still in the 
making ; that is, the pyrite has not replaced all of the rock and some 
of the more resistant materials are still present as a part of the ore. 

is Univ. Calif. Publ., Bull. Dept. Geol., vol. 3, no. 7, 1903. 



1917] Clark: Geology and Ore Deposits of the Leana Rhyolite 375 



A second generation of pyrite occurs in a very fine, dense deposit 
in fracture zones in the first generation. With this later pyrite small 
stringers of chalcopyrite and sphalerite have been deposited contem- 
poraneously. 

The second type of pyrite is much harder in character than the 
type just described, for it contains a considerable amount of silica 
between the partially developed crystals and between the irregular 
masses of the ore. Where the crystals are not in contact they are 
very securely cemented together by a siliceous matrix. Chalcopyrite 
of two generations appears in this pyrite ; some was deposited with 
the pyrite and some has since been deposited along cracks, partially 
replacing the pyrite. Sphalerite and bornite are associated with the 
second generation of chalcopyrite and were probably deposited at the 
same time. One or two small stringers of chalcocite were observed 
along very small fractures in the chalcopyrite. 

The highly silicified country rock, containing a large number of 
irregular masses of pyrite of varying size, seems to represent the first 
stages of metasomatic replacement in the formation of the ore body. 

Genesis of the Ore. — Two general hypotheses may be advanced to 
account for the origin of the pyrite at Leona Heights : 

(1) It was deposited as a metasomatic replacement in the rhyolite 
by magmatic waters along a fracture zone. 

(2) It was formed as a metasomatic replacement in the rhyolite 
by cold descending solutions carrying iron sulphates derived from the 
oxidation of the disseminated pyrite. 

The first of these processes does not seem to have had any part 
in the production of the ore body, for if the sulphides were deposited 
by magmatic waters there would be evidence in the mine of hydro- 
thermal alteration, together with minerals that are thought to be the 
products of ascending thermal solutions ; but nowhere in the mine has 
such alteration been observed or such minerals found. 

The second hypothesis appears to account for the ore at Leona 
Heights. Small deposits of pyrite formed by meteoric waters at 
ordinary temperature have been reported from numerous localities, 
the iron in many cases being supposed to have been derived from the 
ferromagnesian minerals, and the deposition of the pyrite in the 
present instance has been probably brought about by similar processes. 

It is thought that the ore at Leona Heights was formed in a manner 
analogous to that known as the process of secondary sulphide enrich- 
ment. The disseminated pyrite when oxidized at the surface formed 



376 



University of California Publications in Geology [Vol. 10 



iron sulphate and sulphuric acid. These products having been carried 
down by descending meteoric waters to the ground waterdevel, or the 
zone of reduction, lost the free acid and the salt was reduced to pyrite. 
According to Emmons, 14 pyrite oxidizes as follows : 

FeS, + 70 + HX> = FeS0 4 + H 2 S0 4 

6 FeS0 4 + 30 + 3 H 2 = 2 Fe 2 (S0 4 ) :; + 2 Fe(OH), 

Ferric sulphate then breaks down, forming ferric hydroxide and 
sulphuric acid. However, this last step is not always completed in 
the zone of oxidation, for the analysis of mine waters commonly 
reveals the presence of ferric and ferrous sulphates below the zone of 
oxidation. 

It seems probable that most of the iron sulphate is reduced to 
sulphide before the ferric hydroxide stage is reached in the process 
of oxidation, or else limonite would be produced, as pointed out by 
Emmons. 15 He gives the following equations for this last process: 

Fe.,(SO,):, + 6 H 2 = 2 Fe(OH), + 3 H,S0 4 

4 Fe(OH),= 2 Fe 2 : , + 6 H 2 = 2 Fe 2 3 .3 H 2 + 3 H 2 

It seems, then, that whatever the stage in the process of oxidation 
sulphuric acid is produced. 

According to the experiments of Allen, Crenshaw, Johnson, and 
Larsen, 16 pyrite will not form in the presence of a strong acid solution, 
but weak acid or neutral solutions are necessary for the formation 
of pyrite at ordinary temperatures. They also conclude from their 
experiments that neutral solutions and high temperatures favor the 
formation of pyrite, while acid solutions and low temperatures favor 
the formation of marcasite. 

In the light of these facts it seems necessary to explain a method 
of neutralization of the acid formed in the oxidation of the pyrite 
near the surface. When the rhyolite alters it forms kaolin and silica. 
Both of these minerals are very abundant in the altered rock. The 
experiments of Whitman 17 suggest the explanation of at least part 
of the neutralization of the free acid in the sulphate solution. They 
show that basic aluminum sulphate is formed and that pyrite is pre- 
cipitated as a result of the reducing qualities of kaolin. It is a well 

i* Emmons, W. H., The Enrichment of Sulphide Ores, U. S. Geol. Surv., Bull, 
no. 529, p. 48, 1913. 
is Op. cit. 

16 Am. Jour. Sci., ser. 4, vol. 33, p. 169, 1912. 

1 7 Whitman, A. R., Vadose synthesis of pyrite, Econ. Geol., vol. 8, p. 455, 1913. 



1917] Clark: Geology and Ore Deposits of the Leona Rhyolite 377 



known fact that crystals of pyrite, according to Ransome, 18 are found 
in and associated with kaolin, for kaolin is very abundant in the 
oxidized zone at Goldfield, and is also found in the sulphide zone, 
associated with quartz, alunite, and crystals of pyrite. He also states 19 
that pyrite forms a considerable part of the altered rocks, particu- 
larly the dacites and latites that have been altered to alunite and 
kaolin rock. In the Butte district Weed 20 reports pyrite, sericite, and 
quartz as the chief minerals in the altered zones. Mr. Lindgren 21 
gives pyrite as a mineral formed in the zone of secondary sulphide 
enrichment by meteoric waters. 

The Relation of Fracturing to the Ore Deposit. — The rhyolite in 
the vicinity of the ore deposit is intensely fractured, as shown in the 
mine workings. Along most of the fracture planes the fact of move- 
ment is shown by slickensides or gouge. The intensity of the move- 
ment along fractures has been doubtless due to the larger faults that 
traverse this region. The major fault traverses the valley to the west, 
while a minor fault, as shown on the geologic map, extends through 
the hill near the pyrite deposit. The development of this complex 
fracture zone has facilitated the passage of the meteoric waters through 
the acid porphyry in such a way as to cause the localization of the ore 
at this point. It is also possible that the two types of pyrite are the 
products of a continuous period of mineralization interrupted by 
faulting movement. 

The Reducing Effect of the Rhyolite. — The oxygenated meteoric 
waters descending through the intensely fractured acid porphyry 
would react on the feldspars in the wall rock, producing sulphates, 
kaolin, and silica, and it seems probable that by the time these de- 
scending solutions had traveled vertically and probably for some dis- 
tance horizontally through the rhyolite, which was then much thicker 
and wider than at present, they would have become neutral, or even 
slightly alkaline. According to Emmons, 22 acid solutions may become 
neutral, and even alkaline, in a relatively short distance from the 
surface. He says: "There is considerable evidence that acidity de- 
creases below the water-level. Analysis of two samples of water taken 
from a column of water in the Callaway shaft, Ducktown, Tennessee, 
indicate a decrease in acidity of more than 50 per cent within a ver- 

i* Prof. Paper, U. S. Geol. Surv., no. 66, p. 127, 1909. 
» Ibid., p. 113. 

2" Prof. Paper, U. S. Geol. Surv., no. 74, p. 90, 1912. 

21 P>onomic Geology, vol. 2, p. 105, 1907. 

22 Oil. cit., p. 89, 1913. 



378 University of California Publications in Geology [Vol. 10 

tical distance downward of 37 feet. Some of the analyses from the 
Capote mine, Cananea, Mexico, show also a neutralization of acid at 
comparatively shallow depth. The geologic data are comparatively 
in harmony with this conclusion, for there is abundant evidence that 
descending acid waters attack alkaline or alkaline-earth silicates and 
alkaline-earth carbonates ; acid reacting with feldspars or sericite forms 
kaolin, and these reactions are attended by the solution of alkalies or 
alkaline-earths as sulphates." 

It is probable that the sulphate solutions upon reaching the ground 
water-level, or the reducing zone, lost free acid and became neutral. 
The sulphate was then reduced to the sulphide and the pyrite-ore 
body formed as a metasomatic replacement in the rhyolite. 

Prom the character and disposition of the ore deposits at Leona 
Heights it seems probable that the rhyolite at this place is underlain 
by the Knoxville shale ; indeed, from the exposures of this shale near 
by, as shown by the geologic map, it may be safely inferred that the 
shale lies at a comparatively short distance below the present workings 
in the ore body. The ore body described by Mace 23 rests on a carbo- 
naceous shale, and he concludes that organic matter from the shale 
was taken into the underground circulation and produced a local 
reducing water table. The ore, as far as has been exploited, appears 
to have a downward trend or pitch towards the northeast, so that it 
may extend to the shale. The shale may have supplied reducing agents 
in the form of carbonaceous matter and H,S to the ground water. The 
downward percolating water contained in solution the metallic salts. 
The surface of the underground water was probably near the top of 
the shale formation and the water was supplied with carbonaceous 
matter and H 2 S derived from the shale. When the two waters met 
at the water table the ferrous sulphate was completely reduced to 
pyrite. If this be so, the influence of the shale on the chemical con- 
dition of the ground water may have been a potent factor in the local- 
ization of the pyrite deposit. Much light will be thrown on this point 
when the lower limit of the ore is determined, and the probability of 
shale lying not far below the present mine workings should be consid- 
ered in plans for exploitation at lower levels. 



23 Op. cit., p. 1320. 



1 917 ] Clark: Geology and Ore Deposits of the Leona Bhyolite 379 



SUMMARY 

The Leona Rhyolite occupies a narrow belt along the front of the 
Berkeley Hills from Hamilton Gulch at Berkeley to a point about five 
miles southeast of Haywards. 

It comprises a lava flow that probably followed an erosional valley 
along the contact of the Knoxville shale and the Franciscan. The 
rock is very much fractured and has undergone alteration by surface 
agencies. The rhyolite contains pyrite as an original mineral, the 
oxidation of which has colored the surface reddish brown. 

The rhyolite is probably Pliocene or older, and has been quite 
extensively faulted in post-Pliocene time, some of the movements 
occurring in very recent time. 

The petrographical study of the rhyolite shows that it may be 
divided into four distinct facies, based principally on texture. It 
shows a gradual gradation from glassy and spherulitic through por- 
phyritic to felsitic facies. This supports the field evidence that the 
rock probably came from a common source and represents a single flow. 

The chemical analyses show that the rock is a soda rhyolite. 

East of Oakland, near Leona Heights, there are considerable masses 
of potato-shaped bodies of pyrite in the rhyolite. 

The metallographic microscope shows that there are two types of 
pyrite : one soft and massive, and another highly silicified and very 
hard. The ore contains chalcopyrite in very small quantities, which 
was mostly deposited contemporaneously with the pyrite. Traces of 
secondary chalcocite have also been detected. 

The ore deposit was formed as a metasomatic replacement in the 
rhyolite by descending meteoric waters. The ore body is in a frac- 
tured zone determined by a fault in the rhyolite which allowed free 
passage of meteoric water. The reducing condition of the ground 
water may have been induced in part by carbonaceous matter from 
the Knoxville shale that probably underlies the ore body at Leona 
Heights. 



EXPLANATION OF PLATE 25 

Fig. A. Showing the ideal type of spherulite. The number of plates of 
feldspar that make up the spherulites are so small and are in such large numbers 
that the outline of each individual plate is not visible. X 230. 

Fig. B. Showing the spherulites in the ground-mass and in the altered rem- 
nants of phenocrysts. The prismoid crystals that make up the spherulite are 
microscopic in size and do not give a black cross under crossed nicols. X 60. 



[380] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL 



[CLARK] VOL, 10, PL. 25 




Fig. B 



EXPLANATION OF PLATE 26 



Fig. A. A characteristic section of gouge surrounding the soft type of pyrite. 
It generally contains much pyrite and always shows evidence of movement in 
the breccia fragments included in it. Natural size. 

Fig. B. Showing the metasomatie process at work in the formation of the 
hard type of pyrite. (E) Silicified rhyolite. (S) Sulphides. Natural size. 



[382] 



UNIV. CALIF. PUBL. BULL 



DEPT. GEOL. 



[CLARK] VOL. 10, PL 





KC 

ft t\' 



Pleistocene 



Recent 



c 




t 




1 1 1 

<3sa 




• q? 1 ■ * 






9fr 







San Antonio Temescal Formation 
Formation 

With 
Chert-Gravel 
member Qsac 

MATIONS 



Geology by C. W. Clark 
Surveyed in 1916 



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14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13 and 14 in one cover 15o 

15. Notes on the Later Cenozoic History of the Mohave Desert Region in Southeastern 

California, by Charles Laurence Baker 50c 

16. Avifauna of the Pleistocene Cave Deposits of California, by Loye Holmes Miller .... 15c 

17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5c 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25c 



VOLUME 7. 

1. The Minerals of Tonopah, Nevada, by Arthur S. Eakle 25c 

2. Pseudostratification in Santa Barbara County, California, by George Davis Louder- 

back 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Rancho La Brea, by John C. 

Merriam 5c 

4. The Neocene Section at Kirker Pass on the North Side of Mount Diablo, by Bruce 

L. Clark _ 15c 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60e 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 21, pp. 383-420, 4 text-figs., pis. 28-33 November 27, 1917 



THE BRECCIAS OF THE MARIPOSA FORMATION 
IN THE VICINITY OF COLFAX, CALIFORNIA 

BY 

CLARENCE L. MOODY 
CONTENTS 

PAGE 



Introduction 383 

Location and topography 384 

General geology 386 

Stratigraphy of the Mariposa formation 388 

General statement 388 

Slate ._ 389 

Sandstone 390 

Breccia 391 

Occurrence .' 391 

Megascopic features * 394 

Microscopic features 397 

Breccias in other areas of the Mariposa ■. 397 

Palaeontologic evidence 398 

Classification of related conglomerates 399 

General statement 399 

Marine 400 

Fluviatile 401 

Glacial 402 

Fanglomerates '. 405 

Probable origin of the Breccia 406 

Structure 410 

Igneous rocks in the Mariposa 413 

Resume 413 



INTRODUCTION 

The Mariposa formation, which has long interested students of the 
Sierra Nevada, is exceptionally well exposed in the vicinity of Colfax ; 
it is believed that a more favorable locality for the study of its 
stratigraphy will not be found. 



384 University of California Publications in Geology [Vol. 10 



The present investigation was undertaken in the hope of securing 
definite evidence concerning the origin of the uncommon breccia beds 
which comprise about one-fifth of the formation in this vicinity. The 
main purpose of this paper, however, will have been accomplished if 
the attention of geologists is sufficiently called to the peculiarities of 
these beds to inspire a further investigation as to their origin. The 
chief stimulus that has lent zest to the investigation has been the sug- 
gestion by Professor A. C. Lawson that the breccia may be a Jurassic 
tillite. While the results obtained only partially support this view, 
its value as a working hypothesis is acknowledged with pleasure. 

Free use of the folio of the United States Geological Survey cover- 
ing this region has been made during the prosecution of the work. 

LOCATION AND TOPOGEAPHY 

The region studied lies in the southwest quarter of the Colfax 
quadrangle, California ; it embraces an area of 60.5 square miles, with 
a length of 11 miles and a width of 5.5 miles. The accompanying 
map (pi. 28) shows the general features of the geography. Colfax, the 
only town of importance in the vicinity, is about sixty miles northeast 
of Sacramento. 

The small area shown on the map is part of the foothill belt of the 
Sierra Nevada. The relief is pronounced and rapidly increases in 
ruggedness to the north and east, attaining a maximum at the crest 
of the range, about thirty miles northeast of Colfax. The highest 
eminence in the region under consideration is on Cape Horn Ridge 
northeast of Colfax; its elevation is 3100 feet. The lowest point is 
at the bottom of the canon of the North Fork of the American River ; 
the 900-foot contour crosses the stream just south of Owl Creek. The 
maximum relief is thus 2200 feet. 

The dominant features of the topography are the canons of the 
Bear River and of the North Fork of the American River. The Bear 
River takes its course diagonally across the northwestern corner of 
the area mapped. It occupies a large rugged canon, with precipitous 
walls where the stream cuts through the plutonic mass northwest of 
Colfax, but with more gentle approaches in other tracts. Its chief 
tributary is the Greenhorn River with a small catchment basin west 
of Dutch Flat. The average grade of the Bear River within the limits 
of the map is 71 feet to the mile. The North Fork of the American 
River occupies a deeply incised trench with an average slope of the 



UNIV. CALIF, PUBL. BULL. DEPT. GEOL 



[MOODY] VOL. 10, PL. 




1917] 



Moody: Breccias of the Mariposa Formation 



385 



walls of forty degrees. Little difference is to be found in the rate 
of erosion, measured in terms of steepness of slope, in the canon ; 
amphibolite seems no more resistant than the slates of the Mariposa. 
A great number of youthful, tumultuous streams are tributary to the 
North Fork. Robbers Ravine and the nameless gorge just east of 
Colfax drain the rugged region around Cape Horn. South of Colfax 
the drainage is chiefly into Bunch Canon. Live Oak Creek, a tributary 
of Bunch Creek, and Bushy Creek, which flows directly into the North 
Pork, drains the high region around New England Mills. The eastern 
tributaries are Indian Creek, Bushy Creek and Owl Creek, all drain- 
ing the Forest Hill divide just beyond the limits of the map. The 
average grade of the North Fork of the American River is 58 feet 
to the mile. The disparity in grade between the Bear and the American 
rivers has been shown by Lindgren to be due to the weakening of the 
activity of the former caused by the capture of its headwaters by the 
South Fork of the Yuba River in the vicinity of Emigrant Gap. 

At least two cycles of erosion, separated by a period of extensive 
deposition are represented in the region, and each controls in a greater 
or less degree the development of present physiographic features. The 
first cycle appears in the old surface upon which the superjacent series 
was laid down. This surface has been extensively exhumed by the 
stripping away of the gravels and volcanic rocks which have accumu- 
lated since Cretaceous time. The surface is one of subdued relief 
carved in the massive, schistose and slaty rocks of the basement com- 
plex. Tbe remnants of the superjacent series which are found on 
some of the hills determine a second surface of low relief, but of a 
totally different character ; it is a graded, depositional surface. The 
present topography was evolved by the dissection of this graded sur- 
face by streams consequent upon a late uplift of the Sierra Nevada 
block. The present elevation of the range may have been attained in 
a double uplift, the first stage of which caused the removal of most 
of the superjacent series, and the second instituted the vigorous 
erosion that is still continuing in the carving out of the narrow, 
groove-like canons in the basement rocks. The present streams flow 
in V-shaped trenches with abrupt approaches; lateral or tributary 
drainage has not been sufficiently advanced as yet to remove all of the 
once extensive superjacent series ; outliers such as Howell Hill and 
Colfax Hill are abundant and characteristic of this, as of other parts 
of the foothill belt of the Sierra Nevada. In a word the present 
geomorphic cycle is still in a stage of early youth. 



386 University of California Publications in Geology [Vol. 10 



GENEEAL GEOLOGY 

The geology of this small region is typical of the foothill belt of 
the entire Sierra Nevada ; all the rocks, except granite, commonly 
found on the lower slopes of the range, occur within its limits. 

The oldest rocks shown on the map belong to the Calaveras forma- 
tion. In the folio of the United States Geological Survey covering this 
region five divisions of the Calaveras have been recognized, but for 
the purposes of this paper the general term Calaveras suffices. Four 
separate areas appear on the map. The formation west of New 
England Mills consists of a highly compressed series of black, clay 
slates and dark, argillaceous sandstones with several lenses and beds 
of limestone and bluish or grayish chert. The smaller area northwest 
of the Bear River is lithologically similar. Intermediate between these 
two localities on the east bank of the Bear River, directly west of 
Colfax, is a small outcrop of slate and slightly altered sandstone over- 
lain by a thick mass of gray limestone which bears several species of 
lower Carboniferous fossils (see section EP, pi. 28). Forms referable 
to the anthozoan genera, Clisiophyllum and Lithostrotion, together 
with round crinoid stems were collected, while two species of Pleuro- 
tomaria, and one or two spirifiroid brachiopods were observed. In the 
northeastern part of the area the Calaveras rocks are fissile clay slates 
of a brownish to black color with a phyllitic development of mica, 
which gives them a lustrous, silvery aspect when weathered. 

The Mariposa formation of Upper Jurassic age succeeds the 
Calaveras. It is generally regarded as the latest sedimentary forma- 
tion of the Bedrock series. The area shown on the map represents the 
northern limit of a long belt of the formation traceable from Mariposa 
County. In this vicinity it consists of black slates alternating with 
dark gray sandstones and a great number of breccia beds. Its strati- 
graphy will be considered more at length later. 

Igneous rocks are abundant in the area. The amphibolite belt 
which the American River canon follows closely for some distance may 
represent flows contemporaneous with the deposition of the Mariposa 
sediments; long, narrow lenses of black slate included within the 
amphibolite, near the toll-house on the Forest Hill road, suggest this 
contemporaneity. Southward, however, and just east of the limit of 
the map, dikes of a material in every way similar to the amphibolite 
of the main belt clearly cut the Mariposa slate. 

The diabase west of Bear River is regarded by Lindgren as repre- 
senting lava flows possibly antedating the Mariposa depositional epoch. 



1917] 



Moody: Breccias of the Mariposa Formation 



387 



Part of the diabase is certainly irruptive, however ; dikes of a por- 
phyritic facies clearly intrude the Calaveras limestone shown in sec- 
tion EF, and other dikes may be seen crossing the Mariposa contact 
where exposed by the excavations for the Bear River canal. Numerous 
diabase dikes are included wholly within the Mariposa formation. 

Serpentine, in dikes and masses, cuts the Mariposa and older 
formations. Its occurrence in dikes along contacts of both igneous 
and sedimentary rocks suggests that it represents a late phase of 
intrusion. The planes of schistosity of the Calaveras were, however, 
seen to pass obliquely across a serpentine dike near the Bear River, 




AM. Amphibolite; DB, Diabase; SP, Serpentine; 
GB, Gabbro. 

Fig. 1. Generalized columnar section 

though other areas are wholly unsheared ; the possibility of two periods 
of serpentine intrusion is thus indicated. 

The elliptical area of gabbro, northwest of Colfax, is a coarse 
granitic rock of basic aspect, which has invaded the Mariposa, the older 
diabase and the Calaveras. The mapping suggests that this gabbro 
was brought into its present position by anticlinal folding, but its 
irruptive nature is indicated by chilled margins and discordance with 
the strike of the sedimentary beds. 

The only other rocks in the vicinity of Colfax are the volcanic tuffs 
and river gravels of the superjacent series, which appear as outliers 
on the higher eminences of the region. 



388 University of California Publications in Geology [Vol. 10 



STRATIGRAPHY OF THE MARIPOSA FORMATION 
General Statement 

The Mariposa formation is familiarly referred to as the "Mariposa 
slates," and this term is justified when the two long belts of dark 
sediments, stretching from Mariposa County to well north of the 
Mother Lode are considered. In many localities, however, coarser sedi- 
ments are interbedded with the slates ; thus in the Colfax region not 
over half the rocks of the formation are slate. Sandstones and grits 
are here well differentiated from the typical black, slaty argillites. 
Both within the slate and within the sandstone occur numerous beds 
of angular breccia and subordinate conglomerate lenses which persist 
on the strike and form bold ridges in the differential weathering of 
the series. It is estimated that one-fifth the volume of the Mariposa 
beds shown on the map is made up of this coarse material. 

That the Mariposa formation as mapped is a stratigraphic unit 
cannot be denied. The relation of the breccia to the slate in the 
immediate vicinity of Colfax is somewhat obscured by the regolith as 
well as by minor faulting ; but the sections exposed in Live Oak Ravine, 
in the American River canon and on the Forest Hill road in Bunch 
Canon, clearly show a conformable series of slates, sandstones and 
breccias interbedded and in places grading one into the other. 

Columnar sections were made in the field showing the sequence of 
beds in Bunch Canon and in Live Oak Ravine. A gradational series 
from breccia through grit and sandstone to slate is thus made evident. 
The thicknesses of the various members were estimated by pacing the 
horizontal distance. In some cases it was necessary to make arbitrary 
separations of the coarser sandstone from the breccia, and of the slate 
from the sandstone, where no such lines of separation actually exist. 
Some doubt must be entertained as to the number of beds indicated 
because of the possibility of repetition either by folding or faulting. 
The vertical section taken from Bunch Canon, and shown in figure 2, 
is believed to be freer from these sources of difficulty as the dips are 
quite constant, except at R, and the beds are admirably exposed. 
Some indications of repetition by synclinal folding appear at B. If 
the section from P to Q is continuous, twenty-four beds of breccia, 
varying in thickness from two feet to four hundred feet, are inter- 
stratified with twenty-two slate bands, and fourteen beds of sand- 
stone. From the anticline at Q to the intersection of Live Oak Ravine 
with Bunch Canon six breccia beds, eleven sandstone beds and eight 



1917] 



Moody: Breccias of the Mariposa Formation 



389 



slaty bands were counted. In the Live Oak 
Ravine section four heavy breccia beds and 
seventeen sandstone members appear sub- 
ordinate to twelve slate layers, some of 
which are over eight hundred feet thick. 
Frequent alternations of depositional con- 
ditions are thus indicated in Mariposa time, 
but the completeness of the gradations be- 
tween the various lithologic types repre- 
sented, and the large number of minor re- 
currences, make a subdivision of the forma- 
tion impractical. 

The lithologic distinctness of the Mari- 
posa from the Calaveras formation is quite 
marked in the field. The chert, limestones 
and fissile slates and schists which charac- 
terize the latter are wholly lacking in the 
Mariposa. The boundaries are distinct in p 
most places, and the alteration and defor- 
mation are decidedly greater in the older 
series. The conformable, gradational series 
of slates, sandstones and breccias mapped 
as the Mariposa, then, is comprised in a 
well differentiated formation. 

Slate 

The slates of the Mariposa are more con- 
stant in petrographic character than are the 
sandstone and breccias. They are nor- 
mally black, fine-grained shales or slates 
with a well pronounced slaty cleavage. A 
high degree of fissility is not attained by 
the slate ; and arenaceous varieties, grading 
into sandstone, are quite abundant, particu- 
larly in the eastern part of the Mariposa 
belt. The exposures in the ravines and rail- 
road cuts southwest of Colfax are generally 
of a rusty brown color, the result of weath- 
ering; below the regolith the slate is seen to q 
be firm and black. Splendid outcrops of 





Brecci 



Bri 



Coarse 
breccia 



Coarse 
breccia 

Breccia 



Slatv 
breccia 



Breccia 
. Breccia 



Slaty 
breccia 



' Coarse 
breccia 



Breccia 



Breccia 



Sandy 
breccia 



Breccia 



Coarse 
breccia 



Fig. 2. Detailed columnar 
section between P and Q, 
structure section KLM. 
Thickness 5000 feet with 
possible repetition at R. 



390 University of California Publications in Geology [Vol. 10 



bluish-black slate occur in Bunch Canon. The slaty cleavage is here 
wholly conformable with the planes of sedimentation, but this is by no 
means true in every outcrop. In many cases the lines of stratification 
run transverse to the direction of cleavage. Several instances of this 
are to be seen in Live Oak Ravine and in the second right-hand ravine 
tributary to Bunch Canon. Figure 3 shows this feature in the upper 
course of Bunch Creek. 

Microscopically the slate is seen to be composed of a very fine 
aggregate of altered mineral fragments, with an occasional small, 
angular quartz particle recognizable. The largest grain observed was 




Fig. 3. Mariposa slate showing cleavage transverse to 
stratification. Bunch Creek. 



less than 0.5 mm. in diameter. The rock is in no way remarkable ; its 
petrographic features can be duplicated in most of our shale forma- 
tions. Microscopic organisms were searched for in several slides but 
none were found. 

Numerous quartz veins traverse the slate in the southern part of 
the area, but no important mines have been located on them. 

Sandstone 

With an increase in size of particles in the slate, sandstone is pro- 
duced; gradation of particles from the finest up to the size of a pea 
are to be observed in hand specimens. These variable sandstones are 



1917] Moody: Breccias of the Mariposa Formation 391 



more abundant in the eastern part of the area; particularly good 
exposures appear on the Nevada County narrow-gauge railroad near 
the Bear River bridge, and in the middle portion of Bunch Canon. 
The main part of Bushy Canon is cut in this rock. A tendency toward 
slaty cleavage is evident in all the sandstone examined, but this feature 
is far from the perfect development that it attains in the slates. In 
every observed case, this imperfect cleavage is parallel to the strati- 
fication planes. 

Under the microscope the heterogeneity of the sandstone is quite 
marked. The individual particles grade in size from the finest up to 
the largest fragments in the breccia. As has been said, no definite 
line is to be drawn between sandstone on the one hand and breccia 
on the other. Angularity is the rule in the fragments large enough 
to be readily differentiated. Admixed with the angular material, 
however, are many subangular and even rounded grains of quartz, 
feldspar and limestone. The larger fragments are usually composed 
of limestone or chert ; quartzite is commonly present, while fragments 
of amphibole-schist, diabase, basic lava, and slate appear subordinately. 
Plate 33, figure A, illustrates the main microscopic features of the rock. 

The fresh sandstone is normally dark in color, but is locally of a 
greenish cast, due to the presence of chlorite stains. 

BRECCIA 
Occurrence 

The most interesting and unusual lithologic type of the Mariposa 
formation is the coarser variety of clastic here termed "breccia." 1 
Under this head are included the beds in which the larger constituent 
fragments range from the size of a pea up to a foot or more in 
maximum dimension. 

The outcrops of the breccia are very striking, due to the great 
induration of the beds, which are by far the most resistant members 
of the formation. The ridge southwest of the nameless creek south of 
Bushy Canon owes its prominence to a massive bed of this rock. The 
breccia here strikes across the bed of the American River and, because 

i The word "breccia" has never been rigidly defined; it is here employed 
because of its lack of suggestion as to an hypothesis of origin. The term 
"conglomerate" is inapplicable because of the peculiar features of the deposit, 
as well as on account of the unavoidable connotation of ideas of origin which 
accompanies the use of this common, often too loosely applied, word. "Breccia," 
as here used, is a term co-ordinate with "glomerate," recently proposed by 
R. M. Field (Ottawa Nat., vol. 30, p. 31, 1916). 



392 University of California Publications in Geology [Vol. 10 



of its superior hardness, has caused a marked constriction in the 
narrow canon. Other thick breccia layers strike across Bunch Canon 
and in each case the rock shows the same resistance to erosion. So 
thoroughly indurated is the breccia that artificial fractures as well as 
joints transect the included fragments. AVeathered-out fragments are 
rare ; the only places where they are notably developed are on the 
Colfax road, about a mile north of Ne.w England Mills, and near the 
point where the county road leading west from Colfax crosses the 
Bear River. 

Breccia occurs at all horizons throughout the Mariposa, but is 
somewhat more abundant in the eastern part of the terrane ; slate pre- 
dominates in the western part. Thus only four well differentiated 
breccia beds appear in Live Oak Ravine, while twenty-four were 
counted on the Forest Hill road. 

The several small cuts on the Nevada County narrow gauge line 
north of Colfax reveal a number of sandy beds which pass into coarser 
material in places. The second railroad cut south of the Bear River 
bridge is in a coarse, massive angular breccia in which spheroidal 
weathering is well-developed. Several coarse, angular fragments 
form the center of highly silicified sandstone bodies, several feet in 
diameter. These masses stand out prominently in the weathering 
of the cliffs, and might easily be mistaken for extra large boulders in 
the breccia. Their black color and extreme hardness tend to accentuate 
this possibility. Massive outcrops of rather uniformly angular breccia 
are to be seen just below the point where the county road crosses the 
narrow gauge line. Black slates lie above and below this mass. The 
prominent hill, southwest of Colfax, in the broad embayment of the 
triangular diabase area, is composed of coarse breccia with some slate 
beds. In the lower course of the Bear River a few thin beds of hard, 
angular breccia are interstratified with the typical black slates of the 
Mariposa. 

The railroad cuts of the Central Pacific south of Colfax furnish 
excellent exposures of the various rock types of the Mariposa, but 
difficulty is experienced here in deciding as to the relation of the 
breccia to the slate; if it were not for sections showing this relation 
better elsewhere it might be assumed that the breccia was a separate 
formation. Faulting has contributed to the difficulties, but the chief 
of these is the wholly massive character of the breccia. In the second 
cut south of the town, great rounded masses of hard angular breccia 
project through a red mantle of decayed rock. Spheroidal weathering 



1917] 



Moody: Breccias of the Mariposa Formation 



393 



has produced striking exposures ; the larger masses show several ex- 
foliating layers, the smaller, one or two. 

The heterogeneity of the breccia is perhaps better exemplified in 
this cut than in any other exposure visited. One small block contains 
fragments, from one to seven inches across, of chert, quartzite, lime- 
stone, gabbro, diabase, amphibole-schist, and one rounded pebble which 
is apparently a normal granite. 

A splendid section of the entire Mariposa belt is obtained by fol- 
lowing Live Oak Ravine from New England Mills to its juncture with 
Bunch Canon, thence down the Forest Hill road to the amphibolite 
contact near the American River. The first breccia bed exposed in 
this section is well seen on the county road one mile north of New 
England Mills. Here a fifty foot bed of massive, unsorted material 
lies between fine black slates dipping 70° E. Throughout Live Oak 
Ravine coarse material is abundant in the sediments, but only four 
well-individualized breccia beds appear ; the heaviest of these is per- 
haps seventy-five feet thick. Reference has already been made to the 
great number of breccia beds in the lower course of Bunch Canon. 
All are unsorted, heterogeneous members of the series and are inter- 
bedded with slate and sandstone. (See detailed columnar section, 
fig. 2) In thickness the breccia beds range from two feet to four 
hundred feet. In one exposure the breccia is seen to be lenticular. 
Considerable mineralization has affected the Mariposa beds in the last 
two miles of section. Several prospect holes mark attempts to find 
wealth in the unresponsive rocks. One drift has been run over two 
hundred feet into the mountain side. It follows a small dislocation 
plane in the slate ; the gouge has been recemented and sparsely charged 
with pyrite and less abundant chalcopyrite. Quartz and calcite veinlets 
cut through slate, sandstone and breccia indifferently, and the above 
mentioned sulphides are found disseminated in the coarser elastics. 
The last member of the series, west of the amphibolite belt, is a massive 
breccia bed which has been so thoroughly silicified and recemented 
that it presents quite a different appearance from the usual breccia of 
the formation ; it is hard, dense and almost uniformly aphanitic, except 
in favorable spots where differential weathering has left a few frag- 
ments in relief. The rock is pyritized. The Annie Laurie mine, one 
of the more pretentious prospects of the region, is situated on the 
amphibolite contact in this pyritized zone. 

An instructive outcrop occurs in Bunch Canon about one mile north 
of its junction with Live Oak Ravine. At the point where the creek 



394 University of California Publications in Geology [Vol. 10 



crosses the stage road a great bed of breccia has been incised and 
polished by the abrasion of the little stream, so that an extensive sur- 
face is presented for study. Figure A in plate 31 rather inadequately 
shows the locality; a number of tortuous bands of black slate occur 
within a massive bed of coarse breccia. The slate areas which are 
greatly elongated in the direction of the general strike of the breccia 
bed represent muds which accumulated and solidified contemporan- 
eously with the coarse material; some of the slate bands are seen to 
feather out into the coarser sandstone matrix. 

The American River Canon is replete with bold outcrops of the 
breccia. Beds interstratified with slate occur well up to the serpentine 
contact on the west. The exposure is in the bed of the river. Refer- 
ence has already been made to the thick bed of breccia at the small 
suspension bridge which spans the American River at a point about 
one-half mile southwest of Owl Creek. Some of the included boulders 
are rounded ; they range in size up to fourteen inches in diameter. 

Megascopic Features 

Texturally the breccia grades from fine to extremely coarse; this 
gradation is both lateral and vertical and, although usually gradual, 
may be abrupt along the dip. Viewed broadly the breccia is essentially 
a variable aggregate of angular, subangular and rounded boulders, 
for the most part unevenly distributed through a matrix varying from 
coarse sand to fine mud. Sorting action is rare. The variation of the 
coarse material is in four directions, namely abundance, size, composi- 
tion, and degree of rounding. 

Nearly every bed has a different ratio between coarse and fine 
material ; in some cases the fine material is subordinate, in others only 
a few scattered blocks occur in an otherwise medium- grained argil- 
laceous sandstone. In no case, however, is there a total lack of fine 
grained material. 

The average size of the included fragments is approximately one 
inch. By this is meant that most of the pebbles are of this dimension ; 
however, the variation both above and below this figure is so great 
that a wholly inadequate conception of the appearance of the rock is 
conveyed by any statement as to the average size of the component 
fragments. In general the size of the fragments ranges from a frac- 
tion of an inch up to three feet in maximum dimension. The ratio 
of abundance of fragments between two inches and one-half inch to 



1917] 



Moody: Breccias of the Mariposa Formation 



395 



those having a maximum dimension of three feet is estimated to be 
about 100:1. Particles less than one-half inch in diameter are of 
course far more numerous than all the others ; it appeared in the field 
that the material of this size constitutes from three-eighths to one-half 
the volume of the entire rock. Many holes or cavernous spaces, with 
somewhat more restricted limits of size than the included fragments, 
indicate former limestone fragments which have been dissolved in the 
meteoric circulation. 

The A'icissitudes through which the Mariposa rocks have passed are 
not reflected to any great extent in the breccia. The pebbles have 
suffered very little, if any, deformation ; it is only in the finer facies 
that any perceptible shearing planes have been developed. The 
coarser rocks are typically massive ; they fracture indifferently in any 
direction. 

The argillaceous matrix of the breccia is, in the hand-specimen, well 
differentiated from the coarser particles of the rock. It is in every 
way like the black slates with which the breccias are intercalated, and, 
where sufficiently abundant, shows slaty cleavage in the direction of 
prevailing schistosity. 

The pebbles and boulders included in the breccia represent a wide 
range of rock types. Perhaps the most abundant rock represented is 
chert. Black, gray and green fragments, always wholly angular, occur 
in nearly every other outcrop ; they are in no way different from the 
fragments that now mantle the hillsides in the Calaveras area to the 
west. Next in abundance are limestone pebbles usually of a dark gray 
color and either angular or subangular in outline. Rounded as well 
as angular and subangular pebbles of diabase are quite abundant. Of 
equal prominence are quartz pebbles, which on the whole are moder- 
ately well water-worn ; few of them can be called angular. Boulders 
up to a foot in diameter are not uncommon. Subordinately appear 
blocks of gabbro, basic lava, amphibole-schist, mica-schist, slate, friable 
sandstone ami felsite. One pebble showing quartz and feldspar 
twinned on the Carlsbad law was seen in the exposure of massive 
breccia west of Colfax. It seemed to be a typical granite. Fairbanks 2 
also reports granite boulders from the Mariposa in the vicinity. 

Rounded, water-worn material is not wanting in the breccia; in 
fact some of the exposures east of Colfax contain it in some abundance, 
so that the breccia in places passes into normal conglomerate. In the 
main, however, angular and subangular material predominates, and it 

2 Fairbanks, H. W., Jour. Geol., vol. 5, no. 1, p. 76, 1897. 



396 University of California Publications in Geology [Vol. 10 



is this type of fragment that lends distinction to the breccia. In 
general the pebbles are pockety and unsorted and the longer axes of 
the flat fragments often transgress the bedding planes. 

Certain phenomena appear in a study of the disposition of some of 
the coarse blocks which are very difficult to explain without recourse 
to the transporting action of ice. I refer to the rather exceptional 
occurrence of single or nearly isolated boulders, some of them ranging 
in size up to a yard in maximum dimension, entirely within rather 
thin-bedded slate. Plate 33, figure B, shows a chert boulder three feet 
in diameter, in a railroad cut just south of Colfax, which is embedded 
within an arenaceous slate. The boulder is now rather extensively 
broken down by weathering, but it was evidently somewhat rounded 




Fig. 4. Boulders in finer sediments of Mariposa breccia. North Fork of 
American River between Owl and Bushy creeks. 

by water wear before its deposition in its fine-grained matrix. Other 
blocks of a similar nature occur in this outcrop of the breccia. 

The photographs shown in plate 32 were obtained in the bed of the 
North Fork of the American River between Owl and Bushy creeks. 
They illustrate the isolated boulders which are rather abundant 
in the finer sediments prevailing in this cafion. Eight or ten inches 
is the average diameter of the coarser material here observed. The 
boulders all show some evidence of water wear ; some of them may even 
be said to be well rounded. In both the photographs fine-bedded slate 
is observed to pass around the central boulder ; in figure B this may 
be due to shearing, although it has the appearance of original sedi- 
mentation, but in figure A appears a feature which is rather suggestive 



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Moody: Breccias of the Mariposa Formation 



397 



of the impact phenomena sometimes observed where floating ice is an 
important agent of transportation. The accompanying sketch (fig. 4) 
shows diagrammatically the relations in this exposure. A quartzite 
boulder (A) ten inches in diameter, elongated in the direction of the 
bedding of the finer sediments, lies in a depression in a thin slate lens, 
and is overlain by a second slate stratum which arches over it in a 
pronounced curve; in the upper stratum a diabase block (B) is dis- 
tinctly embedded in the fine, slaty material, the sedimentary planes 
coming squarely up to the subangular block and not passing around 
it. The attitude of block B is such that it could not possibly have 
been laid down contemporaneously with the argillaceous material of 
the slate ; it must have been dropped into its present position after the 
upper slate stratum was laid down. This occurrence is, however, not 
typically that observed where evidences of impact are clearly pre- 
served ; no crater development is to be seen in the slaty material sur- 
rounding the boulder. 



Microscopic Features 

A microscopic examination of the breccia was undertaken in the 
hope of gaining some clue as to its origin, as reflected in the nature of 
the matrix. The accompanying photomicrographs (pi. 30) show the 
features revealed in thin section. 

Microscopically the matrix is seen to grade from coarse sand down 
to a fine, felty aggregate which is unresolvable under the microscope. 
Petrographically it is quite similar to the black slate of the series, the 
only difference being that it contains larger recognizable particles. 
These larger particles usually consist of quartz, but some very fine 
chert granules are to be seen. The recognizable fragments, like their 
large relatives, are chiefly angular or subangular (fig. A), although 
somewhat rounded ones also occur (fig. B). The degree of comminu- 
tion, then, is the only apparent difference between the fine and coarse 
phases of the rock. 

BRECCIAS IN OTHER AREAS OF THE MARIPOSA 

The area of the Mariposa beds shown on the map represents the 
northernmost extension of a remarkably persistent narrow belt of 
similar beds which traverses the entire Mother Lode district. Breccias 
are present throughout this extent, and although they vary consider- 



398 University of California Publications in Geology ["Vol. 10 



ably in abundance are apparently nowbere so well developed as in the 
region described. 

The series of breccias of the Colfax area continues into the Placer- 
ville quadrangle to the south. Lindgren and Turner 3 refer to them 
here as "a series of dark, partly volcanic sandstones and breccias 
intercalated among the slates." 

Farther south the breccia becomes less abundant. Near Plymouth, 
in the Jackson quadrangle, occur two or three beds interstratified with 
the clay slates and schistose sandstones. Southwest of San Andreas 
the conglomerate is described 4 as largely replacing the slate. Near 
Angel's Camp breccia and tuff are interbedded with slate. Ransome 5 
regards the Mariposa section of Woods Creek in the Sonora quadrangle 
south of Table Mountain as affording the best exposures in the Mother 
Lode belt. Here are interbedded slates, schistose sandstone and con- 
glomerates. The latter are not always persistent, but often pass 
irregularly into sandstone and slate. These observations tend to show 
that the breccia phenomena are not to be referred to some local, 
peculiar condition ; the agencies which produced them were general 
and widespread. 

On Dry Creek, west of Drytown, Amador County, occurs a ten- 
foot bed of. brecciated material consisting of fragments of quartz, 
quartzite. chert, limestone and various igneous rocks, ranging from 
angular to well-rounded in outline and cemented by a phyllitic matrix. 
This bed was mapped by Ransome as a part of the Calaveras forma- 
tion, but as mentioned in the text of the Mother Lode folio, its relations 
to the Mariposa were not plain. It may belong to the series which runs 
north to Colfax. Dr. Adolph Knopf, who has first hand knowledge of 
the occurrence, is of the opinion that this bed represents either a 
fanglomerate or a tillite with the probabilities favoring the latter 
hypothesis. 

PALAEONTOLOGIC EVIDENCE 
The fauna of the Mariposa formation throughout its whole extent 
is sufficient to place the age of the beds as Upper Jurassic. Dr. 
Stanton and Professor J. P. Smith concur in this determination. 
Within the limits of the area studied, however, only two forms have 
been discovered which are of palaeontologic significance. These are 

3 Lindgren, W. and Turner, H. W., IT. S. Geol. Surv. Folio, no. 3. 
* Ransome, F. L., U. S. Geol. Surv. Folio, no. 63. 
s Loc. cit. 

« Personal communication. 



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Moody: Breccias of the Mariposa Formation 



399 



Perisphinctes colfaxi Gabb, found in the railroad cut one mile south 
of Colfax, and Olcostephanus lindgrcni Hyatt, which occurs in rusty, 
brown, sandy slate about one-half mile west of the first locality. These 
ammonites point to an Upper Jurassic age. 

Since these fossils have been obtained from beds with which the 
breccias are interstratified, it was thought well to obtain what evidence 
they furnish as to the climatic conditions under which the deposits 
formed. In answer to a request for such information, Professor J. 
P. Smith replied : 7 ' ' The fossils of the Mariposa do not give much 
indication as to climate except that they are all of northern kinship. 
That may not mean cold, though it possibly means a cooler climate 
than the Middle Jurassic." 

The occurrence of ammonites in the slate, however, indicates that 
this portion of the series at least is marine, and any hypothesis explain- 
ing the origin of the beds must take cognizance of this fact. 

CLASSIFICATION OF RELATED CONGLOMERATES 
General Statement 
In arriving at a correct understanding of the origin of the Mariposa 
breccias it will be necessary to review in a few words the various con- 
glomerate types now recognized and to institute comparisons between 
them and the rock under discussion. 

Such a study was made ten years ago by G. R. Mansfield 8 in an 
investigation of the stratigraphy of the Boston Basin, and his results 
have proved of great value in the preparation of this paper. He 
divided conglomerates into six types, classified on the basis of their 
origin, as follows: (1) marine, (2) fluviatile, (3) estuarine, (±) 
lacustrine, (5) glacial, (6) crush-conglomerate. Of these (4) and (6) 
require no further consideration since the Mariposa breccias are inter- 
stratified with marine beds, and since the heterogeneity of the pebbles 
precludes the possibility of their formation by the brecciation of any 
single rock. There then remain for consideration marine, fluviatile, 
estuarine, and glacial conglomerates. To these must be added an 
important class of clastic deposits recently described by Professor 
A. C. Lawson as fanglomerate. The origin of the Colfax rocks is 

t Personal communication. 

s Mansfield, G. R., The origin and structure of the Roxbury conglomerate, 
Bull. Mus. Comp. Zool. Harvard College, no. 49, Geol. ser., vol. 8, no. 4, 1906. 

9 The petrographic designation of alluvial fan formations, Univ. Calif. Publ. 
Bull. Dept. Geology., vol. 7, no. 15, 1913. 



400 University of California Publications in Geology [Vol. 10 



certainly comprised in the processes which have given rise to the above 
mentioned types, but the fact must not be lost sight of that two or 
more processes may have operated to produce the breccias. 

Marine 10 

Typical marine conglomerates have clean, well-marked and sorted 
sand as a matrix. When in quantity the sand may be more or less 
cross-bedded ; the grains vary from angular to rounded. The com- 
ponent pebbles of the rock are usually of material of local origin ; 
they are uniform in size and are ordinarily well rounded. The strati- 
fication of marine conglomerates is usually well marked and cross- 
bedding may be more or less perfectly developed. In the normal cycle 
of sedimentation, following an encroaching sea, finer material will 
overlie the coarse and may locally interdigitate with it. Local un- 
conformities and irregularities may be expected along the dip but great 
persistence and uniformity is common along the strike. In general, 
true marine conglomerates are not thick; Barrell 11 states that their 
thickness is usually less than one hundred feet. 

Mansfield has cited the Cretaceous of Texas as a typical example 
of a series of marine deposits. The Trinity sands, described by Hill, 12 
as the basal formation, have as their lowest member a fine pebble 
conglomerate, consisting of small masses of the adjacent pre-existing 
rocks in a cement of ferruginous yellow and red gritty sand. Most 
of the coarser material is well rounded and sorted, though in some 
localities it is predominantly subangular with only the more resistant 
quartz, which has travelled a long distance, well rounded. The basal 
conglomerate grades upwards into sands, grits, and silts; it is seldom 
over two hundred feet thick. Both massive and well-bedded deposits 
occur in the formation ; sands and clays are interstratified with the 
conglomerate in places, while elsewhere the beds are dominantly coarse. 

Other typical marine conglomerates, deposited in an encroaching 
sea, are abundant in the stratigraphy of the western part of the United 
States. Among them might be mentioned the Scanlon and Barnes 
arkosic conglomerates described by Eansome 13 from the Globe district. 

The following points of difference may be pointed out between the 
Mariposa breccias and typical marine deposits of that type: (1) 

10 Mansfield, loc. cit., pp. 107-150. 

11 Barrell, J., Abstract: Bull. Geol. Soc. Amer., vol. 20, p. 620, 1909. 

12 Hill, B. T., Twenty-first Annual Beport, U. S. Geol. Surv., pt. 7, 1901. 

13 Eansome, F. L., U. S. Geol. Surv. Frof. Faper, no. 12, pp. 30-31, 1903. 



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Moody: 



Breccias of the Mariposa Formation 



401 



angular material predominates in every exposure of the Mariposa; in 
some, no rounded material is visible; (2) the pebbles are unsorted, 
distinct bedding is often lacking; (3) the matrix is largely silty. 

Pluviatile 

Conglomerates referable to stream action usually have a matrix of 
sand mixed with fine and coarse material which is, in general, not well 
sorted and may be cross-bedded ; the individual grains vary from 
angular to partly rounded. The coarser material ordinarily consists 
of locally derived masses which may range up to several tons in weight ; 
the boulders vary from well-rounded to subangular. Frequent alter- 
nations of coarse and fine beds, both commonly showing current mark- 
ings, oblique lamination and numerous irregularities in thickness and 
composition characterize such deposits. The thickness of flood-plain 
conglomerates may be very great. 

Instances of conglomerates of this type are to be found all over 
the world. The Siwalik Group, a Tertiary deposit of India, with a 
maximum thickness of 14,000 feet is regarded by Geikie 14 as of fluviatile 
origin. Fluviatile deposits occur in the upper Old Red Sandstone of 
Great Britain, 15 in the High Plateaus of Utah, described by Dutton, 10 
where angular material predominates and in the Great Valley of 
California as discussed by Ransome. 17 The auriferous gravels of the 
Sierra Nevada form one of the most typical of fluviatile deposits yet 
described. 

The predominance of rounded and subangular pebbles in typical 
fluviatile conglomerate is not realized in the Mariposa beds. As will 
appear in the sequel, however, it is believed that streams of high grade 
may have been instrumental in transporting the material which now 
makes up the formation. 

The deposits termed "estuarine" 18 by Mansfield are not essentially 
distinct from those of fluviatile origin ; as he uses the term it is appar- 
ently intended to be restricted to the deposits accumulated in the delta 
portion of streams. This class of deposits is summarized by Bailey 
Willis 10 in the following statement : 

The unassorted mingling of sandy and clayey particles is the result of 
rapid deposition at the mouths of muddy streams in opposition to waves that 
are too weak to sort and distribute the volume of sediment. This is a condition 

14 Geikie, A., Textbook of Geology, ed. 3, p. 1021. 
is Op. cit., ed. 3, p. 802. 

is Report on the geology of the high plateaus of Utah, 1880. 

it Ransome, F. L., Univ. Calif. Publ. Bull. Dept. Geol., vol. 1, no. 14. 

is Loc. cit., pp. 121-122. 

19 Willis, Bailey, Maryland Geol. Surv., vol. 4, p. 63, 1902. 



402 



University of California Publications in Geology [Vol. 10 



of delta building. The frequent and irregular interbeddimg of coarse sands, 
sandy clays and clays, the cross-stratified beds, the ripple-marked and sun- 
cracked mud surfaces, the channels scoured by transitory streams, all prove the 
abundance of sediments, the shifting conditions of deposition, the irregularity 
of currents, the wide expanse of tide-flats and shallow waters and the weakness 
of the waves. 

The admixture of flue and coarse material and the frequent alter- 
nations in the series at Colfax conform very well to this general type 
of delta deposits. Cross-bedding was, however, not observed in these 
rocks, and other evidences of current action even in the less coarse 
sediments are not at all apparent. 

Glacial 

The consolidated debris transported by glacial agencies has been 
termed "tillite" by Professor Penek. Glacial deposits are character- 
istically heterogeneous aggregates of finer and coarser material, com- 
pacted but wholly unsorted. The matrix of the coarser phases usually 
consists of angular grains of minerals and rocks, fresh feldspar and 
quartz in very finely divided particles being especially abundant. 
The individual grains of the matrix are commonly partly rounded and 
partly angular. The coarser pebbles and boulders are generally 
locally derived, but considerable proportions may come from distant 
sources. Within a tillite, little if any assortment is to be expected; 
masses up to several tons in weight may repose in an argillaceous 
matrix. The shape of the pebbles in a glacial deposit is of great 
diagnostic significance. Such ice-borne fragments are faceted occa- 
sionally and sometimes have their edges rounded and ends snubbed. 
The surface of at least a few of the pebbles is sure to be polished and 
striated, with the majority of the striae paralleling the long axis of 
the stone. Tillites are usually not bedded, although some may show 
an obscure stratification ; sometimes pockets, lenses, and beds of coarser 
and finer false-bedded material may be included in the unstratified 
mass. 

Such deposits as above described are due to the deposition of 
material as moraines, eskers and kames, but. other types of glacial 
deposits are known. Thus in glacial-fed streams a well differentiated 
type of deposit results which may here be termed fluvo-glacial ; all 
gradations from typical tillite to well-marked fluviatile deposits may 
be anticipated in such a deposit. In the case of a glacier directly 
facing the sea, the reworked till may be sorted and well-bedded and 



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Moody: Breccias of the Mariposa Formation 



403 



usually exhibits sharply individualized beds of coarse and fine material 
alternating in a variable sequence. 

The importance of glaciers as agents of transportation and deposi- 
tion both in early as well as late geologic time is now generally 
accepted. Shaler and Davis. 20 as early as 1881, recognized, beside 
Quarternary glaciation, evidence of glacial action in the Superga 
Miocene of Italy, in the Eocene of Switzerland, in the Chalk of 
England, in the Jurassic of Scotland, in the Triassic of eastern 
United States, and in the Permian, Subcarboniferous (Mississippian) , 
Devonian, upper Silurian and Cambrian in various areas throughout 
the earth. Their views have been somewhat modified by later work, 
but deposits referable to glacial agencies have since been found of 
even greater age than they then surmised. No general exception then 
can be taken to the possibility of glaciation in the Mariposa. 

The Permo-Carboniferous Talchir group of India described by 
"White, 21 Oldham and others is a typical glacial deposit. It consists 
of 500-800 feet of clays, fine silts, boulders, sandy shales, conglomer- 
ates, and soft sandstones. The included fragments are everywhere 
subangular, and are mostly derived from distant localities. Large 
boulders often lie embedded in silt too fine to admit any explanation 
except that of deposition from floating ice. Smoothed and striated 
stones are frequent in the unsorted masses. 

Boulder beds very similar to those of India occur in New South 
Wales, Australia, and in South Africa. The Dwyka Conglomerate 
in the latter area is now well known in the literature of glaciology. 
A good description of this formation is given by Mellor. 22 The rock 
is usually bluish or green and consists of fragments of a number of 
mineral species. Within the mud matrix are included a vast number 
of boulders and pebbles of a variety of rocks, scattered irregularly and 
indiscriminately throughout its mass. Many of the boulders are 
rounded ; many others are flattened and striated in two or more direc- 
tions. Lenticular patches of shales and mudstones, apparently de- 
posited in pockets in the conglomerate, consist of the finest glacial 
mud. Professor Davis 23 remarks that since no marine deposits are 
associated with the formation, which extends over thousands of miles, 
he considers that the Dwyka ice was a continental sheet analogous to 
the Pleistocene glaciers of the northern hemisphere. Beautifully 

20 Shaler and Davis, W. M., Glaciers, p. 102, 1881. 

21 White, C. D., American Geologist, vol. 3, p. 299, 1889. 

22 Mellor, E. T., Quar. Jour. Geol. Soc, vol. 61, pp. 683-86, 1905. 
2-'i Davis, W. M., Bull. Geol. Soc. Amer., vol. 17, p. 413. 



404 University of California Publications in Geology [Vol. 10 



glaciated rock floors are found underlying the formation in various 
localities. Oldham and others have correlated the Dwyka with the 
Australian tillite and with the Talchir group of India. 

In North America the recognition of the glacial origin of the basal 
conglomerate of the Cobalt series marks an important advance in our 
knowledge of geological history. To A. P. Coleman 24 is due the credit 
of this important discovery. "Wherever exposed the lower part of the 
Cobalt series is seen to be a wonderfully thick, heterogeneous con- 
glomerate. Hore 25 gives a good description of the rock. It consists 
of a great variety of types and sizes of boulders with very little sorting 
in evidence. Large, isolated boulders sometimes occur in clay slates ; 
the larger masses are usually rounded or subangular, some are 
markedly angular. The matrix is ordinarily graywacke with an 
occasional slate pocket; numerous particles of quartz, feldspar, chert 
and felsite are to be seen under the microscope. Some fine-grained 
turbid matter in the matrix contains chlorite, thus differing from the 
Dwyka. Within the deposit, sudden lateral and vertical changes often 
occur ; shales are frequently interbedded with coarse material ; quartz- 
ites, rapidly grading into akrose, interdigitate with the coarser facies. 
Coleman 26 describes and figures well-preserved striations on some of 
the boulders ; they show best on f elsites and fine-grained greenstones ; 
many of the surfaces are well polished. In the Cobalt tillite it has 
been possible to differentiate various types of glacial debris ; thus 
widely separated fragments in a medium-grained matrix indicate 
ground moraine ; wholly coarse material is considered as representing 
the terminal moraine, while various aggregates of rudely sorted, 
rounded pebbles mark the sites of ancient kames. In arriving at a 
conclusion as to the origin of the Cobalt conglomerate, Coleman con- 
sidered and rejected hypotheses involving crushing, faulting, talus 
formation, and exceptionally heavy -river currents. The tillite is inter- 
bedded with slate layers up to five hundred feet in thickness, which are 
considered to represent deposition during interglacial periods. The 
formation stretches over thousands of square miles and thus probably 
indicates the extension of a great ice-sheet over the continent in that 
remote time. 

Other ancient tillites in America have been found by Sayles 27 in 

-* Coleman, A. P., Jour. Geol., vol. 16, pp. 149-158, 1908. 
as Hore, E, E., Jour. Geol., vol. 18, no. 5, pp. 459-67, 1910. 

26 Loc. ext. 

27 Sayles, E. W., Harv. Mus. Comp. Zool., vol. 56, no. 2, 1914. 



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Moody: Breccias of the Mariposa Formation 



405 



the Boston Basin, and by Atwood 28 in the Eocene of southwestern 
Colorado. The probability of a glacial origin for the Mariposa breccia 
will be considered later. 

Fanglomerates 

This term was proposed by Professor Lawson 29 as a petrographic 
designation for the coarser portions of alluvial fan formations. 
Aridity and high relief are postulated in ascribing a fan origin to a 
deposit. The constituents of a fanglomerate range from the coarsest 
material down to fine sand. Blocks of extraordinary size are apt to 
appear at the apex of a fan, and occasional ones, a foot or more in 
diameter, are found far down the slope where the average size of the 
material is less than one inch in maximum dimension. A gradation 
in size of material from coarse to fine is, however, to be anticipated 
as one progresses from the apex to the lower slopes of such a forma- 
tion ; the normal sequence is fanglomerate, arkose, silt, the latter 
representing playa, lake or river flood-plain detritus. In any given 
point within an alluvial fan formation sorting action is very imper- 
fect ; the sorting is chiefly that represented by the gradational change 
from coarse to fine material in a lateral direction. The cement of a 
fanglomerate cannot be fine grained; silt only appears near the playa 
end of a fan. In general the matrix of such a deposit will be medium 
to coarse sand. Of course infiltration may later cement the rock to 
such an extent that it will fracture indifferently through, rather than 
around, the included fragments. The masses included in a fan- 
glomerate can never have traveled a great distance ; they are usually 
of the same composition as the steep mountain slopes at the base of 
which they lie. Occasional water-worn boulders are to be found 
admixed with angular to subangular material which makes up the 
greater portion of the rock. 

The argillaceous matrix of the Mariposa breccia is considered a 
serious objection to an hypothesis of origin involving typical alluvial 
fans of the desert type. Further, since marine beds are certainly inter- 
stratified with the breccias, even though they themselves were not laid 
down in the sea, the conditions for the formation of typical fan- 
glomerates were certainly not realized. The probability of desert- 
fans having played a part in the origin of the beds under consideration 
is, then, held to be rather remote. The conception of alluvial deposits 

28 Atwood, W. A., U. S. Geol. Surv. Prof. Paper, no 95-B, 1915. 

29 Op. cit. 



406 



University of California Publications in Geology [Vol. 10 



developed under the humid cycle is, however, believed to furnish 
a possible solution of the problem of origin. 

PROBABLE ORIGIN OP THE BRECCIA 

We have here to deal with a normal conformable series of strata 
progressing in the main from coarse to fine, although occasionally 
exhibiting a sudden discontinuous change from fine to coarse. The 
slaty faeies of the series is of marine origin; the breccia, which is 
interbedded with it, must clearly have been deposited in a marine 
basin. The problem is then to explain the occurrence of angular 
pebbles in a fine arenaceous to a silty matrix. 

It is obvious that wave action must have been at a minimum during 
the period of accumulation of the coarse material. It is equally cer- 
tain that transportation by fluviatile agencies took place if at all only 
through short distances. The material of the larger fragments is all 
derived from the Calaveras rocks exposed in the immediate vicinity, 
comprising chert, limestone, slate, sandstone, and schists of various 
types, as well a.s the more common basic igneous rocks, which make up 
this older series. Quartz pebbles alone seem to have been transported 
some distance; quartz veins do occur in the Calaveras, but they may 
belong to the same period of mineralization which affected the Mari- 
posa at the time of the production of the great Mother Lode belt to 
the south, but as these pebbles are in general rounded they may be 
considered to have come from a distance. 

In discussing the evidence for the Mariposa-Calaveras unconformity 
Turner 30 states that the two distinct belts of the Mariposa in and 
south of the Jackson quadrangle were deposited in long, narrow 
troughs between Calaveras ridges, and that later the beds were infolded 
with the Carboniferous series. Intrusive and extrusive igneous action 
as well as adjustment of stresses through folding and perhaps fault- 
ing prepared a Jurassic surface of marked relief in which two long, 
narrow basins roughly parallel and striking in a northwest-southeast 
direction, connected with the open sea probably to the southeast. These 
troughs received the sediments which we now know as the Mariposa 
beds. 

The opinion of Lindgren 31 as to the origin of the Mariposa of the 
Colfax region is expressed as follows: "The formation was clearly 

so Turner, H. W., Fourteenth Annual Report, U. S. Geol. Surv., pp. 456-457, 
1892. 

si Lindgren, W., U. S. Geol. Surv. Folio, no. 66, p. 3. 



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Mooch): Breccia* of the Mariposa Formation 



407 



deposited in a gulf or shallow bay, the conglomerates indicating the 
immediate proximity of the shore line." 

Two alternative hypotheses of origin merit consideration ; the first, 
is that the breccias are consolidated glacial debris, the second, that 
they represent alluvial material derived under the humid cycle. The 
latter theory is essentially only an extension of the views of Lindgren 
and Turner. 

The Mariposa breccias unquestionably resemble many typical 
tillites. The admixture of rounded, subrounded and angular boulders 
in an unsorted matrix of leas coarse material, which is often silty, is 
a feature which characterizes all tillites from the most ancient to the 
most recent. Interbedding of such glacial deposits with slates is 
rather a common feature ; several slate beds are intercalated in the 
Cobalt tillite, they characterize the Dwyka of Africa, and in the 
Permo-Carboniferous tillite of Australia, six slate horizons, bearing 
a marine fauna, alternate with the coarser glacial beds. In addition 
to these characteristics common to all well authenticated tillites, 
positive evidences of glacial action, particularly the striating and 
faceting of pebbles, are observed in the actual deposits, while in most 
cases a polished, fluted and striated surface is found underlying the 
morainal material. Such lines of evidence are of course actual demon- 
strations of extensive glaciation, but their apparent absence cannot be 
held to disprove any hypothesis of glacial origin. Careful search in all 
the outcrops of the Mariposa in the vicinity of Colfax have so far 
failed to reveal any typically glaciated pebbles. Some striations were 
observed, but all these appeared to be due to cracks or weaknesses in 
the rock; flattened and snubbed pebbles were nowhere found. Further, 
the surface upon which the Mariposa beds were laid down is very 
poorly exposed in the region ; the western Calaveras contact is the 
only one which might offer an opportunity for observation ; the other 
contacts are against irrupted masses. Unfortunately this only known 
normal contact is covered throughout with rock-waste. It is thus 
unknown whether or not the formation rests on a glaciated surface. 
However, since marine beds are interstratified with the coarse deposits, 
if their origin is to be referred to glacial action, the glaciated floor 
from which the debris was swept would probably be outside the marine 
basin in which the deposits accumulated, and, as acute deformation 
and extensive denudation have affected the region, resulting in the 
removal of a larger part of the rocks which bordered the basin, the 
discovery of a glaciated surface is hardly to be expected. Dr. Knopf 



408 University of California Publications in Geology [Vol. 10 

has suggested that striations might become obliterated during the 
vicissitudes through which the beds have passed; the Dwyka, Talchir 
and Australian Permian tillites in which striated pebbles are so 
abundant, have suffered very little of the intense deformation which 
has visited the Mariposa. The remarkable preservation of striations 
on pebbles from the Cobalt tillite, however, shows that once the seal 
of glaciation is imprinted it becomes well-nigh ineradicable. It should 
at this point be noted that many Pleistocene moraines yield few or no 
striated pebbles, so that their original absence does not seriously affect 
the evidence favoring a glacial origin for the beds. 

In the great glacial horizons of the world the slates interbedded 
with tillites are generally interpreted as representing interglacial 
periods or temporary retreats of the ice. At least eight such changes 
of conditions of deposition are recorded in the Colfax rocks. 

The strongest indications found of the action of ice are phenomena 
which are usually referred to the agency of ground-ice. The isolated 
boulders in the slaty beds are rather strongly indicative of the kind 
of rafting which is, with much reason, attributed to the floating action 
of icebergs or of river-ice. No other agency seems to account satis- 
factorily for the appearance of sporadic rounded boulders in such 
fine-grained sediments. The presence of ground-ice of course implies 
less rigorous climatic conditions than are entailed in the assumption 
of extensive glaciation. Average temperatures somewhat below the 
freezing point of water would be required only during the winter 
months to produce river-ice in sufficient abundance to account for the 
transportation of the erratic material observed in the Mariposa slates. 

Should future investigations reveal positive evidence of glacial 
action within the Mariposa breccias, then the sporadic, disconnected 
areas of the coarse detrital material may well be explained by the 
rafting action of icebergs. 

The second hypothesis proposed for the origin of the beds postulates 
the bounding of the structural troughs, which admitted the late 
Jurassic sea to the region, by rifts or abrupt monoclinal folds which 
presented fronts of high relief toward the basins of accumulation. 
Early Jurassic streams of low grade may be inferred, since the region 
was in the zone of erosion throughout Pennsylvanian and Triassic 
time. Some of these streams would doubtless maintain their courses 
across the structure imposed in the late Jurassic ; it is these antecedent 
streams as well as the subsequent-consequent streams, i.e., those fol- 
lowing the trend of the structural troughs, which may be considered 



1917] 



Moody : 



Breccias of the Mariposa Formation 



409 



to have supplied the silty material that now forms the slates, and 
much of the less triturated clastic that is comprised in the sandstones. 
The lateral boundaries of the basins, presenting such bold relief, would 
be vigorously attacked by the forces of weathering and their shoreward 
slopes would furnish abundant rock-waste which, accumulating at 
their base, would spread out as alluvial fans, the outer margins passing 
well under the shallow waters of the adjoining arm of the sea. 
Weathering in a humid climate produces fine-grained material nor- 
mally which approaches the texture of clay ; if feldspathic rocks are 
being reduced, much kaolin may indeed be mixed with the sandy mass. 
Siliceous rocks however are apt to fracture into angular pieces, which 
in time of maximum precipitation, travel down the slope and become 
intermingled with the finer material produced more slowly ; igneous 
rocks likewise tend to fracture and split into angular fragments, and 
they too become part of the growing fan. Rapidly growing high-grade 
consequent streams developed in the degradation of a steep front, soon 
cut back by headward erosion far enough so that material transported 
from the headwaters, by the time it has reached the lower courses, 
shows considerable rounding, while in times of freshet, subangular 
fragments are supplied in abundance. Here, then, is a mechanism 
which furnishes a heterogeneous mixture of coarse material grading 
from wholly angular to well rounded, with a silty to sandy matrix. 
Progressive subsidence of the floor of the basin of deposition must 
have occurred to accommodate the very considerable thickness of 
sediments. If this progressive lowering of the basin took place in 
stages, as, for example, by movements along a zone of faulting, or by 
intermittent down-folding on a monocline, the frequent alternations 
from coarse to fine sediments observed within the series are readily 
accounted for. 

The conditions of deposition along the eastern margin of San 
Francisco Bay present helpful analogies with the conditions which 
may have existed during the filling up of the Mariposa troughs. A 
fault-zone, known as the Haywards Rift, separates a region of con- 
siderable relief from the comparatively low-lying plane upon which 
Berkeley is situated. Angular material is furnished by the rapid 
degradation of the Berkeley Hills, while the Sacramento-San Joaquin 
river systems supply the bay with the silty material which may in 
time become consolidated into shale or even slate. If the present land 
surface west of the fault-zone were lowered slightly below the bay- 
level, conditions would be realized in which fine material could mingle 



410 



University of California Publications in Geology [Vol. 10 



with coarse, and a series of beds, in every way similar to the Mariposa, 
would be laid down. 

Great persistence on the original dip is not to be anticipated under 
such conditions, and several instances have been cited where the 
Mariposa breccias grade laterally into sandstone and slate. Since 
the dips are all high it has not been found possible to trace many of 
the beds into fine sediments. The lack of cross-bedding in the Mari- 
posa series is not considered a serious objection to its estuarine origin 
under the conditions described, because it is under just such conditions 
that current action is at a minimum; tidal action being spread over a 
long shore line nearly equally, would not favor false stratification 
although the chief role in the intermingling of the differently derived 
sediments must be assigned to this agency. 

The sporadic distribution of boulders through some of the slate 
members constitutes the most serious objection to an hypothesis of 
origin involving alluviation ; their presence must be accounted for in 
some other way. The alternate hypothesis of ground-ice transporta- 
tion is the only one which suggests itself as reasonably accounting for 
this uncommon distribution. 

The assumption of rifting or monoclinal folding as the agency 
which outlined the Mariposa basin is not violent in the light of later 
events in the history of the Sierra Nevada. That lines of weakness 
existed in the earth 's crust in this region, trending in the same general 
direction, is abundantly witnessed by the great shearing-stresses that 
imposed a slaty cleavage on the rocks at the close of the Jurassic. 

STRUCTURE 

The Mariposa beds, in the area studied, have a structure imposed 
upon them which in detail is complicated, but which in its broad 
features is comparatively simple. The beds have been folded into a 
series of anticlines and synclines due to eompressional forces acting in 
a northeast-southwest direction. The general strike of the structure 
is northwest-southeast. 

The folding does not seem to have been as intense in the northern 
part of the belt as in the southern. The dips are gentler and the folds 
are more open in the vicinity of Colfax. In the Live Oak Ravine- 
Bunch Canon section (sec. K L M, pi. 29) it is very difficult to make out 
the position of the several folds since the whole series has been closely 
compressed and overturned ; a careful measurement of dip changes 
affords the only method of deciphering the structure here ; even at 



UNIV. CALIF. PUBL, BULL. DEPT. GEOL. 



[MOODY] VOL. 10, PL. 29 




Structural sections 



1917] Moody: Breccias of the Mariposa Formation 411 

best a high degree of accuracy cannot be attained. In the more open 
folds exposed along the Bear River and in the railroad cuts south of 
Colfax comparatively little difficulty of this nature is experienced. 
The approximate structural relations are shown in the seven sections 
on plate 29. 

A fault is indicated in the sections but has not been placed upon 
the map. The long straight contact north of Cape Horn most certainly 
represents a dislocation of some magnitude. In the Colfax folio, 
Lindgren 32 states that the angular discordance at this contact is due 
to an unconformity, but since the younger beds are truncated by the 
contact plane (see sees. AB, CD, GH) their present position can be 
due only to a fault. No crushing is to be seen at the contact but this 
does not seriously weaken the evidence for the existence of the dis- 
location. 

Faulting within the Mariposa itself is locally abundant but large 
dislocations were not recognized. Three well-defined minor faults 
affecting the slates were observed in a railroad cut one mile south of 
Colfax. In the creek east of Colfax a marked discordance of dip 
occurs in the slate; nearly horizontal beds are seen lying on the up- 
turned jagged edges of the lower strata, with considerable kataclastic 
matter intervening. 

The slaty cleavage that now characterizes the Mariposa beds was 
superposed on an already folded system of rocks. That this is true is 
proved by the not infrequent occurrence of planes of slaty cleavage 
cutting the original bedding planes. This phenomenon was observed 
only in the slate ; the sandstone and breccia members always conform 
to the shearing planes. Figure 3 shows the slaty cleavage almost 
normal to the planes of sedimentation. 

Viewed broadly the Mariposa rocks are to be considered as uncon- 
formably overlying the Calaveras and infolded with them in the great 
diastrophic paroxysm that affected the region at the close of the 
Jurassic. Evidence of structural unconformity is, however, hard to 
discover in the field. The western contact is obscured by debris north 
of Howell Hill, and south of this point a serpentine dike has appeared 
between the two formations. The eastern contact is regarded as a 
fault and the northern limit is an irruptive mass. When deformation 
is considered, however, the Mariposa rocks appear much younger than 
the Calaveras. 

An exposure just east of Colfax station, at the south end of the 

32 Lindgren, W., U. S. Geol. Surv. Folio, no. 66. 



412 University of California Publications in Geology [Vol. 10 

steep cliff facing west, may have an important bearing on the question 
of unconformity, and moreover, may in time furnish positive evidence 
supporting the glacial hypothesis. Here a chert body, containing 
radiolarian remains, and apparently belonging to the Calaveras series 
exposed to the west, is overlain by the breccia. If a depositional con- 
tact, this section shows profound erosion between the two formations. 
The general structure at this point is anticlinal, so that the chert may 
reasonably be explained as the basement upon which the Mariposa was 
laid down, now brought to the surface in the axis of the anticline. 
Professor Lawson and Professor Louderback with a party of graduate 
students from the University of California visited the locality and 
exposed a small area of the surface of the chert underlying the breccia 
in a search for evidence of glacial scouring. Three grooves were found, 
at least one of which was regarded by Professor Lawson as suggestive 
of ice sculpture, but as minor faulting has affected the whole region, 
positive evidence distinguishing the marks from slickenside phenomena 
was not obtained. 

Angular discordance of dip is shown at the limestone outcrop 
already mentioned on Bear River, but its significance is probably not 
far-reaching. The Calaveras slates, which underlie the limestone 
bearing a Carboniferous fauna, have a north-south strike and a vertical 
dip ; the Mariposa slates in the immediate vicinity strike northeast and 
southwest with dips ranging around sixty degrees. This small isolated 
area of Calaveras rocks is regarded by Lindgren 33 as representing a 
block torn loose from the main area at the time of the intrusion of the 
diabase which bounds the Mariposa to the northwest. Movements 
at this time might account for the discordance, hence the occurrence 
is not regarded as conclusive proof of angular unconformity. 

The palaeontologic evidence of course indicates a profound break 
between the two formations, as does the occurrence of the abundant 
erosional debris of Calaveras rocks in the Mariposa. 

Exact figures on the thickness of the Mariposa in the Colfax region 
cannot at present be given. In the columnar section shown in figure 2, 
however, a minimum of 2500 feet may be stated with some confidence, 
and the probability entertained that this estimate should be increased 
to 5000 feet. The possibility of a repetition at R has been mentioned. 
The amphibolite to the east is not to be considered the top of the 
formation ; the contact may well be a pre-Tertiary fault. With the 
present data an upper limit of thickness is thus not assignable. 

33 Lindgren, W., U. S. Geol. Surv. Folio, no. 66. 



1917] Moody: Breccias of the Mariposa Formation 



413 



IGNEOUS ROCKS IN THE MARIPOSA 
Dikes and masses of diabase and serpentine intrude the Mariposa 
formation at various localities, while a gabbro stock invades its 
northern limits. Their occurrence may be dismissed with the statement 
that little or no contact metamorphism has been induced in the sedi- 
ments by their intrusion. 

RESUME 

The Mariposa is a comfortable, gradational series of breccias, 
sandstones and slates, intruded by a gabbro mass in its northern 
limits. Structurally the beds have suffered isoclinal folding which, 
toward the north, becomes more open. Slaty cleavage parallels the 
bedding in the sandstone but frequently cuts the stratification planes 
of the slate. 

All gradations occur in the sediments from fine mud up to masses 
a yard or more across. The coarser material is dominantly angular 
to subangular, although well rounded pebbles, chiefly quartz, do occur ; 
the matrix is arenaceous to silty. The recognizable fragments could 
all have been derived from the associated Calaveras rocks. 

Suggestions of glacial action or at least of the transporting agency 
of ground-ice or of icebergs appear in the sediments, but high grade 
streams consequent upon folding or faulting in a northwest-southeast 
direction, frequently rejuvenated by recurrent movements, may have 
provided the coarse material which makes up the breccia ; and low 
grade streams, flowing longitudinally with respect to the Mariposa 
troughs, may have transported the fine detritus and more rounded 
pebbles, now forming a large part of the deposit. 

The chief difficulties to be met in the way of a glacial hypothesis 
of origin are (a) lack of positive glacial evidence; (6) the large 
number of alternations of slate and breccia. Any normal process of 
alluviation, however, fails to explain the occurrence of sporadic pebbles 
and boulders in a silty matrix. 



EXPLANATION OF PLATE 30 

Fig. A. Photomicrograph of finer faeies of Mariposa breccia showing the 
predominance of angular material. 

Fig. B. Photomicrograph of breccia showing rounding of some particles. 



[414] 



UNIV. CALIF. PUBL. BULL, DEPT. GEOL 



[MOODY] VOL. 10, PL, 30 




Fig. B 



EXPLANATION OF PLATE 31 

Pig. A. Exposure of breccia in Bunch Canon in which slate slabs occur in 
the finer clastic material. 

Fig. B. A lenticular body of medium-grained breccia interbedded with slate 
on the Forest Hill road. 



[416] 



UNIV. CALIF. PUBL. BULL. DEPT. GEOL. 



[MOODY] VOL. 10, PL, 31 




EXPLANATION OF PLATE 32 

Pig. A. A large boulder embedded in fine slate. The surface is scoured by 
the flood waters of the American River. 

Pig. B. Another scoured surface in the American River Canon showing 
fairly large sized blocks sparsely distributed through a slaty matrix. 



[418] 



UNIV. CALIF. PUBL. BULL, DEPT. GEOL 



[MOODY] VOL. 10, PL. 32 





EXPLANATION OF PLATE 33 

Fig. A. Microphotograph of thin section of Mariposa sandstone. 

Fig. B. Boulder of chert three feet in diameter embedded in an arenaceous 
slate. Railroad cut south of Colfax. 



[420] 



UNIV. CALIF. PJBL. BULL. DEPT. GEOL. 



[MOODY] VOL. 10, PL. 33 




rig. a 




Fig. B 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 22, pp. 421-443, 1 text-figure Issued November 16, 1917 



RELATIONSHIPS OF PLIOCENE MAMMALIAN 
FAUNAS FROM THE PACIFIC COAST AND 
GREAT BASIN PROVINCES OF 
NORTH AMERICA 



BY 

JOHN C. MERRIAM 



I 



UNIVERSITY OF CALIFORNIA PRESS 
BERKELEY 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 



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Cited as Univ. Calif. Publ. Bull. Dept. Geol. 

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A list of titles in volumes 1 to 5 will be sent upon request. 

VOLUME 6. 

1. The Condor-like Vultures of Rancho La Brea, by Loye Holmes Miller 15« 

2. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part I. — Geologic History'. 50c 

3. -The Geology of the Sargent Oil Field, by William F. Jones 25c 

4. Additions to the Avifauna of the Pleistocene Deposits at Fossil Lake, Oregon, by 

Loye Holmes Miller 10c 

5. The Geomorphogeny of the Sierra Nevada Northeast of Lake Tahoe> by John A. Reid 60c 

6. Note on a Gigantic Bear from the Pleistocene of Rancho La Brea, by John C. 

Merriam. 

7. A Collection of Mammalian Remains from Tertiary Beds on the Mohave Desert, 

by Jehn C. Merriam. 

Nos. 6 and 7 in one cover 10c 

8. The Stratigraphic and Faunal Relations of the Martinez Formation to the Chico 

and Tejon North of Mount Diablo, by Roy E. Dickerson 5c 

9. Neocolemanite, a Variety of Colemanite, and Howlite from Lang, Los Angeles 

County, California, by Arthur S. Eakle 10c 

10. A New Antelope from the Pleistocene of Rancho La Brea, by Walter P. Taylor.... 5c 

11. Tertiary Mammal Beds of Virgin Valley and Thousand Creek in Northwestern 

Nevada, by John C. Merriam. Part II. — Vertebrate Faunas 1-00 

12. A Series of Eagle Tarsi from the Pleistocene of Rancho La Brea, by Loye Holmes 

Miller _ 10c 

13. Notes on the Relationships of the Marine Saurian Fauna Described from the Triassic 

of Spitzbergen by Wiman, by John C. Merriam. 

14. Notes on the Dentition of Omphalosaurus, by John C. Merriam and Harold C. Bryant. 

Nos. 13 and 14 in one cover 15o 

15. Notes on the Later Cenozoic History of the Mohave Desert Region in Southeastern 

California, by Charles Laurence Baker 50c 

16. Avifauna of the Pleistocene Cave Deposits of California, by Loye Holmes Miller .... 15c 

17. A Fossil Beaver from the Kettleman Hills, California, by Louise Kellogg 5c 

18. Notes on the Genus Desmostylus of Marsh, by John C. Merriam 10c 

19. The Elastic-Rebound Theory of Earthquakes, by Harry Fielding Reid 25c 

VOLUME 7. 

1. The Minerals of Tonopah, Nevada, by Arthur S. Eakle 25c 

2. Pseudostratification in Santa Barbara County, California, by George Davis Louder- 

back 20c 

3. Recent Discoveries of Carnivora in the Pleistocene of Rancho La Brea, by John C. 

Merriam '. 5c 

4. The Neocene Section at Kirker Pass on the North Side of Mount Diablo, by Bruce 

L. Clark 15c 

5. Contributions to Avian Palaeontology from the Pacific Coast of North America, by 

Loye Holmes Miller 60e 



UNIVERSITY OF CALIFORNIA PUBLICATIONS 

BULLETIN OF THE DEPARTMENT OF 

GEOLOGY 

Vol. 10, No. 22, pp. 421-443, 1 text-figure Issued November 16, 1917 



RELATIONSHIPS OF PLIOCENE MAMMALIAN 
FAUNAS FROM THE PACIFIC COAST AND 
GREAT BASIN PROVINCES OF 
NORTH AMERICA* 

BY 

JOHN C. MEERIAM 



CONTENTS 

PAGE 



Introduction 421 

American Pliocene raunas 424 

Pacific Coast province 424 

Great Basin province 427 

Great Plains province 434 

Atlantic province 438 

Time relations of American faunas 439 

Correlation with Old World faunas 442 



INTRODUCTION 

Much less than a decade ago the imperfection of our knowledge 
of North American Pliocene mammal faunas was so evident that it 
merited comment. Questions frequently arose concerning the relative 
paucity of mammalian remains and of formations representing this 
period, and explanation of the absence of Pliocene records included 
suggestion that the faunas had been largely described as Miocene or 
Pleistocene, or that conditions of relief had been unfavorable for 
accumulation of continental deposits. 

As recently as 1909 Pliocene mammalian life known west of the 
Rocky Mountains was practically all comprised within seven more or 
less doubtfully determined species from the Rattlesnake Pliocene of 

* Read before the Palaeontological Society, Albany, New York, December 27, 
1916. 



nian in**/. 



W N0V2719' 



422 University of California Publications in Geology [Vol.10 



the John Day Valley and several doubtful species from the imper- 
fectly understood Idaho beds of Idaho. At that time the Great Plains 
Pliocene fauna included the Blanco of Texas, and the Republican 
River doubtfully referred to the same period. The Atlantic fauna 
consisted of the intermixed Alachua Pliocene and Peace Creek Pleisto- 
cene, and offered a serious problem in age determination by reason of 
this mixture. 

Seven years ago description of the Snake Creek fauna, the richest 
of all American Pliocene mammal assemblages, by Matthew and Cook 1 
gave the first definite indication of existence of an important Pliocene 
stage other than that of the Blanco. Immediately following the first 
study of the Snake Creek came discovery of the interesting Thousand 
Creek Pliocene fauna 2 of Nevada, with suggestion of similarity to the 
Nebraska Snake Creek in a number of peculiar types, especially in 
the presence of antelopes like those of the Old World Pliocene and 
Miocene. Following the discovery of the Thousand Creek there came 
to light on the western border of the continent the Ricardo fauna 3 of 
the Mohave Desert, the Etchegoin, 4 and the Pinole Tuff-Orinda 5 faunas 
of middle California, while the Rattlesnake fauna of eastern Oregon 
was increased to dimensions comparable to those of the Thousand 
Creek, Ricardo, and Blanco. Additional information regarding the 
composition and age of the interesting fauna of the Idaho formation 
in southwestern Idaho has also been obtained. 

Through the work of Dr. E. H. Sellards, the Alachua fauna of 
Florida has received valuable additions, and has had separated from 
it a considerable number of the elements of more modern aspect, which 
have heretofore confused interpretation of this assemblage. 

Although at the present time American Pliocene mammal faunas 
are not as fully known as those of other Tertiary divisions, progress 
in accumulation and classification of material within the past five 
years has been relatively more rapid than for any other division of 

i Matthew, W. D., and Cook, H. J., A Pliocene fauna from western Nebraska, 
Bull. Amer. Mus. Nat. Hist., vol. 26, pp. 361-414, 1909. 

- Merriam. J. C, Tertiary mammal beds of Virgin Valley and Thousand 
Creek in northwestern Nevada, pt. 2, Vertebrate faunas, Univ. Calif. Publ. Bull. 
Dept. Geol., vol. 6, pp. 199-304, pis. 32-33, 1911. 

3 Merriam, J. C, Extinct faunas of the Mohave Desert: their significance in 
a study of the origin and evolution of life in America, Pop. Sci. Monthly, pp. 
245-264, March, 1915. 

* Merriam, J. C, Tertiary vertebrate faunas of the North Coalinga region of 
California, Trans. Amer. Philos. Soc, n. s., vol. 22, pt. 3, 44 pp., 1915. 

5 Merriam, J. C, Vertebrate fauna of the Orindan and Siestan beds in middle 
California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 373-385, 1913. 

e Eighth Ann. Rep. Florida Geol. Surv., pp. 92-100, 1916. 



1917] 



Merriam: Pliocene Mammalian Faunas 



423 




Fig. 1. Outline map illustrating principal occurrences of Pliocene mammal 
faunas in Tertiary provinces of that portion of United States west of the Wasatch 
Eange. The most important localities are indicated as follows : I, Idaho beds ; 
Ir, Ironside Pliocene; Et, Eattlesnake ; T, Thousand Creek; PO, Pinole Tuff- 
Orinda; ET, Etchegoin-Tulare; C, Chanac; E, Eicardo. 



424 University of California Publications in Geology [Vol. 10 



the Cenozoie. We begin now to see for the first time the broader 
world relationships of our higher vertebrate Pliocene life. 

Of American Pliocene faunas, those represented in the Pacific 
Coast and Great Basin provinces have been so imperfectly known that 
it seems desirable to present a general statement of their composition 
and relationships for use in consideration of certain fundamental 
faunal problems involved in later Cenozoie history. 

AMERICAN PLIOCENE FAUNAS 
Pacific Coast Province 

At the present time there are known in the Pacific Coast province 
at least four important occurrences of Pliocene mammalian remains, 
and there are probably represented in these stations four fairly dis- 
tinct stages or horizons. These are the upper and middle and lower 
Etchegoin on the western border of the San Joaquin Valley ; the 
Tulare overlying the Etchegoin of the Great Valley of California; 
the Chanac formation of the Tejon Hills at the southern end of the 
San Joaquin Valley, and the Pinole Tuff-Orinda section of the 
Mount Diablo or San Francisco Bay region. Of these formations, the 
Etchegoin- Tulare section is not less than 10,000 feet in thickness; 
the Pinole Tuff-Orinda section represents at least 5000 feet of strata ; 
the Tejon Hills section so far as known represents only a few hundred 
feet of accumulation. 

The faunal sequence of the Pacific Coast region is exceptionally 
well represented in the Etchegoin-Tulare section, but the amount of 
material from the beds of that region is unfortunately scanty. Within 
the limits of the Etchegoin two or perhaps three faunal zones are 
known. There is apparently a clear distinction between the upper 
zone characterized by the presence of Pliohippus proversus, a very 
advanced horse like the Blanco Pliohippus, and the middle zone dis- 
tinguished by the presence of Pliohippus coaling ensis, a typical Plio- 
hippus. Below the horizon of P. coalingensis several fragmentary 
specimens of Hipparion have been found, but as yet no remains of 
hipparions are known from the P. coalingensis and P. proversus 
zones. The lowest beds have been discussed in a tentative way as the 
Hipparion zone. 

In the Tulare formation overlying the Etchegoin no certainly 
authenticated occurrences of mammalian remains are reported. About- 



1917] 



Merriam: 



Pliocene Mammalian Faunas 



425 



twenty years ago a specimen of Hyaenognathus, a peculiar dog like 
Borophagus of the Blanco Pliocene, was found associated with Ischy- 
rosmilus, a machaerodont cat, near the town of MeKittrick, in a 
formation now presumed to be Tulare. 

The fauna of the Tulare-Etchegoin section on the western border 
of the San Joaquin Valley is as follows : 

Fauna of Tulare-Etchegoin Section 

TULARE 

fHyaenognathus pachyodon Merriam 
flsehyrosmilus ischyrus (Merriam) 

etchegoin 

Pliohippus proversus zone 

Pliohippus proversus Merriam 

Camelops or Pliauehenia, sp. 

Proeamelus?, sp. 

Cervus or Odocoileus, sp. 

Tayassu or Mylohyus?, sp. 

Mastodon 

Testudo?, sp. 

Undetermined fragmentary fish remains 
Pliohippus coalingensis zone 

Pliohippus coalingensis (Merriam) 
Pliohippus?, sp., small 
Proeamelus?, sp. 
Platygonus ?, sp. 
fHipparion zone 

Neohipparion molle Merriam 
Neohipparion, sp. 
Protohippus or Pliohippus, sp. 

In the Pinole Tuff-Orincla section scattered remains have been 
found at a number of localities, but the best representation of the 
fauna found at any one station is that secured from the Pinole Tuff 
and Orinda on the border of San Pablo Bay. In these strata there 
have been obtained the following forms: 7 

Pinole Tuff-Orinda Fauna, San Pablo Bay 
Pliohippus, near fairbanksi Merriam 
Pliohippus, sp. 

Khinocerotid, near Teleooeras 
Antelope, near Sphenophalos 
Mastodontine form 
Edentate, megalonyehid 
Tephroeyon, sp. 
Testudinate remains 



1 From unpublished manuscript of Merriam and Stock. 



426 University of California Publications in Geology [Vol.10 



At localities in the Orinda, and in beds presumed to be higher 
than those of the horizons at San Pablo Bay, the following forms have 
been obtained : 8 

Orinda Fauna, Contra Costa Hills 
Hipparion platystyle Merriam 
Hipparion, near mohavense Merriam 
Prosthennops, sp. 
Proeamelus, sp. 
Pliauchenia, sp. 
Tetrabelodon ?, sp. 
Dipoides lecontei (Merriam) 

If any suggestion of sequence is given in the Pinole Tuff-Orinda 
section, it appears to be that Hipparion occurs at a horizon somewhat 
higher than that of the Pliohippus forms ; but the stratigraphic suc- 
cession is so imperfectly known that such a conclusion seems not at 
present to be fully warranted. 

The Tcjon Hills fauna found in the Chanac formation at the 
southern end of San Joaquin Valley occurs in beds which rest upon 
marine San Pablo Upper Miocene, and are presumably unconformable 
upon that formation. The fauna includes the following forms: 

Chanac Fauna 
Protohippus tehonensis Merriam 
Pliohippus, sp. 

Hipparion gratum tehonense Merriam 
Hipparion, near molle Merriam 
Rhinoeerotid, indet. 
Prosthennops, sp. 
Camelid, indet. large 
Meryeodus, near necatus Leidy 
Proboscidean (Tetrabelodon?), sp. 

In this fauna the hipparions are the most abundant forms. They 
represent two small species, one of which is very close to Hipparion 
gratum of the Great Plains region. The Prosthennops suggests the 
Pliocene species of the Great Valley of California. The Meryeodus 
is near necatus Leidy, which appears both in the Barstow Upper 
Miocene and in the Ricardo Lower Pliocene of the Mohave Desert a 
few miles to* the east. 

Comparison of the Chanac fauna with the available Etchegoin and 
Tulare faunas shows that the Tejon Hills stage may be comparable 

s Merriam, J. C, Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 373-385, 1913. 

9 Merriam, J. C, Mammalian remains from the Chanac formation of the 
Tejon hills, California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 10, pp. 111-127, 
1916. 



1917] 



Merriam : 



Pliocene Mammalian Faunas 



427 



to the Hipparion-bearing beds in the lowest portion of the Etchegoin 
section. The Pinole Tuff-Orinda fauna seems certainly older than the 
Pliohippus proversus zone of the Etchegoin. The fauna of the beds 
furnishing the best collections of the Pinole Tuff and of the lowest 
Orinda on San Pablo Bay is close to that of the Pliohippus coalin- 
gensis zone of the Etchegoin. The Tulare evidently represents the 
latest stage. 

The sequence of Pliocene faunas and formations of the Pacific 
Coast province as we now know it is most satisfactorily expressed in 
a series of four stages. All four of these faunas may be present in 
one stratigraphic sequence in the North Coalinga region. 

The stages are as follows : 

Tulare fHyaenognathus zone 

Upper Etchegoin Pliohippus proversus zone 

Middle Etchegoin Pliohippus coalingensis zone 

Lower Etchegoin or Chanac ... Hipparion gratum tehonense or Hip- 

parion molle zone 



Great Basin Province 

In the Great Basin region there are four important occurrences 
of Pliocene faunas. These are the Thousand Creek of the northern 
Nevada or Middle Basin area, the Ricardo of the Mohave Desert, the 
Rattlesnake of the John Day Valley, and the Idaho of southwestern 
Idaho. 

The Rattlesnake fauna has unusual significance owing to excep- 
tional clearness of stratigraphic relations of the beds in which it occurs. 
The Rattlesnake formation rests in marked unconformity in steep cliff 
section upon the Mascall, which contains a mammalian fauna of 
Middle or Upper Miocene age. Through the accumulated Rattlesnake 
deposits deep canons have been cut, and in the lower reaches of these 
excavations are deposits containing a Pleistocene fauna. The age of 
the Rattlesnake formation is therefore limited on one side by a period 
of erosion and deformation succeeding accumulation of the Mascall 
Miocene, and on the other side by a period of erosion preceding accum- 
ulation of deposits of Pleistocene age. 

Within the past field season a party from the Department of 
Palaeontology of the University of California has made intensive study 
of the Rattlesnake formation and fauna, and has increased the list of 
mammalian species considerably. 



428 



University of California Publications in Geology [Vol. 10 



The mammal forms now known from the Rattlesnake formation 
are the following : 10 

Rattlesnake Fauna 

Camivora 

?Canis davisi Merriam 

Amphieyon, near amnicola Matthew and Cook 
Mustela, sp. a 
Mustela, sp. b 
Felis, large sp. 

Indaretos? oregonensis Merriam, Stock, and Moody 
Edentata 

Megalonyehid, gen. and sp. indet. 
Rhinocerotidae 

?Teleoceras fossiger (Cope) 
Equidae 

Hipparion sinclairii Wortman 

Hipparion, near occidentale Leidy 

Hipparion, near anthonyi Merriam 

Pliohippus, near fairbanksi Merriam 

Pliohippus speetans (Cope) 
Suidae 

Prosthennops, sp. 
Camelidae 

Alticamelus altus (Marsh) 

Pliauchenia, sp. 

Procamelus, sp. 
Antelojunae 

Sphenophalos, near nevadanus Merriam 

Ilingoceros?, sp. 
Mastodontinae 

Tetrabelodon ?, sp. 
Rodentia 

Lepus?, sp. 

Dipoides?, sp. 

Of the Rattlesnake horses, the best represented Pliohippus forms 
are much like those in the Pliohippus coalingensis zone of the Etche- 
goin, in the Thousand Creek, and in the Ricardo. The Hipparion 
species are like forms of the Thousand Creek and show some resem- 
blance to a species from the Hipparion zone of the Pacific Coast 
province. 

The Rattlesnake antelopes resemble those of the Thousand Creek 
fauna. 

The Thousand Creek fauna is known from extensive exposures in 
the valley of Thousand Creek at the extreme northern border of 
Nevada. The stratigraphic relations of the Thousand Creek formation 
are unfortunately not as yet fully known, but there is every reason 

10 From unpublished manuscript of Merriam, Stock, and Moody. 



1917] 



Merriam: Pliocene Mammalian Faunas 



429 



to consider that the beds are much later than those of the Virgin 
Valley Middle Miocene, which is of approximately the same facies as 
the Mascall Middle Miocene of the John Day region. 

The fauna obtained in the Thousand Creek region is as follows: 11 

Thousand Creek Fauna 

Eeptilia 

Ophidian remains 
Aves 
— Branta, sp. 
Insectivora 

Seapanus ?, sp. 
Carnivora 

Tephroeyon, near kelloggi Merriam 

Aelurodon, sp. 

Canis? davisi Merriam 

Ursus'?, sp. 

Mustela furlongi Merriam 
Mustelid, indet. 

Taxidea nevadensis Butterworth 
Pseudaelurus, sp. 
Felis, sp. a 
Felis, sp. b 
Eodentia 

Aretomys nevadensis Kellogg 
Aretomys minor Kellogg 
Citellus, sp. 

Aploilontia alexandrae Furlong 
Mylagaulus monodon (Cope) 
Dipoides, sp. 

Dipoides lecontei (Merriam) 
Entoptychus minimus Kellogg 
Peromyseus antiquus Kellogg 
Peromyscus?, sp. 
Diprionomys parvus Kellogg 
Diprionomys magnus Kellogg 
Hypolagus vetus (Kellogg) 
Ungulata 

Pliohippus, near fairbanksi Merriam 
Hipparion, near oceidentale Leidy 
i Neohipparion leptode Merriam 
Teleoceras, near fossiger (Cope) 
Mastodon (Tetrabelodon?), sp. 
Pliauehenia 1, sp. 

Camel, ef. Camelus americanus Wortmau 
Prosthennops?, sp. 
Large suilline form 
Splienoplialos nevadanus Merriam 
Ilingoceros alexandrae Merriam 
Ilingoceros scliizoeeras Merriam 

ii Merriam, J. C, Univ. Calif. Publ. Bull. Dept. Geol., vol. 6, pp. 199-304, 
pis. 32-33, 1911; also Butterworth, E. M., Univ. Calif. Publ. Bull. Dept. Geol., 
vol. 10. pp. 21-24, 1916. 



430 University of California Publications in Geology [Vol.10 



The Thousand Creek fauna is characterized by the presence of 
numerous antelopes, some of which are presumably near the modern 
prong-horn, Antilocapra. Others show superficial resemblance to 
strepsicerine types of the Old World. The Thousand Creek fauna 
resembles that of the Rattlesnake in many respects. The horses are 
similar, and the only representation of the peculiar Thousand Creek 
antelopes known outside of the typical region are found in the Rattle- 
snake. The rarity of antelopes in the Rattlesnake may be due to 
chances of collecting, to difference in habitat, or to somewhat later 
age of the Thousand Creek beds. 

Antelope remains found recently in the Pinole Tuff-Orinda fauna 
of San Pablo Bay suggest a relationship between the Thousand Creek- 
Rflttlesnake and the Pinole Tuff-Orinda stage. 

The Rieardo fauna of the Mohave Desert area is found in a for- 
mation comprising between 3000 and 5000 feet of sharply deformed 
strata situated at the eastern foot of the Sierra Nevada Range. The 
beds in which the fauna occurs consist in a large part of tuffs with 
desert conglomerates or fanglomerates and other deposits formed on 
land or in evanescent water bodies. In the thick Rieardo formation a 
moderate variation of the mammals is noticeable in comparison of 
different horizons, but the fauna seems to be a unit not divisible into 
sharply separated stages. 

The species known from the Rieardo are as follows : 

ElCARDO FAUNi. 

Eeptilia 

Testudo, sp. 
Carnivora 

Canid, small 

Aelurodon, near wheelerianus, n. sp. a 
Aelurodon, n. sp. b 
Aelurodon, n. sp. c 
Aelurodon? or Tepkroeyon, sp. 
Isehyrosmilus osborni, n. gen. and sp. 
Felid, large 

Felid, small, not Isehyrosmilus 

Mustela buwaldi, n. sp. 
Eodentia 

Lepus?, sp. 
Equidae 

Hipparion mohavense Merriam 

Hipparion mohavense eallodonte Merriam 

Pliohippus tantalus Merriam 

Pliohippus fairbanksi Merriam 

Pliohippus, near mirabilis (Leidy) 



1917] 



Merriam: Pliocene Mammalian Faunas 



431 



Proboscidea 

Tetrabelodon?, sp. 
Oreodontidae 

Merycoehoerus (Pronomotherium) californicus, n. sp. 
Camelidae 

Procamelus, sp. a 

Procamelus, sp. b 

Pliauchenia, sp. 

Alticamelus ?, sp. 
Bovidae 

Merycodus, near neeatus Leidy 

In contrast with other Pacific Coast and Great Basin faunas the 
Ricardo is characterized by the presence of hipparions of an Old 
"World type with Pliohippus, Merycodus, and an advanced oreodont 
near Pronomotherium. The Ricardo is in every respect a less advanced 
fauna than the Idaho. It is distinguished from the Thousand Creek- 
Rattlesnake stage by the presence of Merycodus, and an oreodont ; by 
the presence of hipparions with round protocone rather than the 
Neohipparion type with flat protocone ; and by absence of highly 
specialized antelopes and of rhinoceroses. The presence of such an- 
cient types as Merycodus and an oreodoiit in the Ricardo indicates an 
earlier stage than Thousand Creek-Rattlesnake from which these types 
are absent. It is, moreover, possible that the Thousand Creek an- 
telopes are descendants of the Ricardo Merycodus. Geologic evidence 
tending to support the age determination based upon palaeontologic 
data is found in the greater degree of induration and deformation of 
the Ricardo. 

The Idaho beds of Oregon were named by E. D. Cope, 12 who de- 
scribed from them a considerable series of fishes. Beds referred to 
the Idaho extend over a large area bordering the Snake River Valley 
in southwestern Idaho, and presumably reach into southeastern Ore- 
gon. They are several hundred feet in thickness and exhibit a slight 
degree of deformation at certain localities. The beds are generally 
unconsolidated, but may show considerable induration and form steep 
cliffs. Lindgren 13 collected a mammalian fauna from exposures pre- 
sumed to he of the same age as the Idaho of Cope. The remains ob- 
tained by Lindgren were determined as Pliocene by F. A. Lucas. 
In the summer of 1916 collections were made at a number of localities 
in this region by J. C. Merriam and J. P. Buwalda for the United 
States Geological Survey. 

12 Cope. E. D., Proc. Amer. Philos. Soc, Nov., 1870, pp. 538-547; also Prop. 
Acad. Nat. Sci. Phila., p. 125, June 26, 1883. 

is Lindgren, W., 20th Ann. Eep. TJ. S. Geol. Surv., pt. 3, p. 99, 1900. 



432 University of California Publications in Geology [Vol. 10 



The fauna reported from beds referred to the Idaho formation is 
as follows : 

Fauna Referred to Idaho 
Equus idahoensis, n. sp. 
Equus excelsus? Leidy 
Protohippus ? 

Rhinoceros, probably Aphelops (Teleoeefras) fossiger (Cope) 
Mastodon miriflcus Leidy 
Procamelus, size of P. major (Leidy) 

Cervus, possibly new, slightly smaller and more slender than C. canadensis 

(Erxleben) 
Horn-core of true antelope (Tragocerus?) 
Ischyrosmilus, n. sp. 
Morotherium leptonyx Marsh 
Castor, possibly n. sp. 
— Olor, size of O. palaeocygnus 
Graeulus idahoensis Marsh 

The Idaho formation is not as yet satisfactorily separated from 
the Payette Eocene or Miocene, and from a Miocene or Pliocene stage 
which may intervene between the Payette and the Idaho. It is, how- 
ever, quite certain that there exists over a large area of southwestern 
Idaho a formation several hundred feet thick which may show evidence 
of deformation, and which contains a fauna of a stage representing 
either the latest Pliocene or the earliest Pleistocene. 

Mammalian remains presumed to represent the Idaho have been 
reported from a number of localities of which the relative geologic 
position is uncertain. One might assume from the composition of the 
entire list of forms obtained by Lindgren that the collections are in 
the main from beds of Pliocene age, with the possibility that some of 
the elements are derived from Pleistocene deposits, and possibly some 
from horizons older than typical Idaho. 

Of the several mammalian types listed by Lindgren, the horses are 
undoubtedly the most important for palaeontologic determination of 
age. The only form specifically determined in the earlier collections 
was one considered by Leidy to represent Equus excelsus. This species 
is not known from beds older than Pleistocene. Bones from near 
Sommercamp Ranch, in the northern portion of the Silver City quad- 
rangle, have been referred to Protohippus. If this determination is 
correct, these beds might be Pliocene or late Miocene. Horse remains 
obtained at Idaho localities by Buwalda and Merriam in 1916, in the 
course of investigations carried on for the United States Geological 
Survey, are of a type clearly to be referred to Equus. In the lowest 
beds examined at a locality on the Snake River, southwest of the town 



1917] Mcrriam: Pliocene Mammalian Faunas 433 

of Caldwell, the bottom of the section furnished material representing 
a very advanced equine form not distinguished from Equus 
on the basis of size or of advance in specialization of feet and teeth. 
This species does not seem to the writer specifically identical with any 
thus far described in America. It differs from the Pliohippus pro- 
versus type of the upper Etchegoin Pliocene in the typical equine 
character of the upper cheek-teeth, as shown by the inner wall of the 
protocone, the fossettes, and the outer walls of the paracone and meta- 
cone ; so that it must be included within the genus Equus. On the 
other hand, it differs from the described Pleistocene forms of Equus 
in the shorter protocone, which approaches the type of pillar in Equus 
stenonis of the Old World Pliocene. 

A rhinoceros from exposures considered as Idaho, east of Boise, 
was referred to Aph clops (Teleoceras) fossigcr. This form represents 
the late Miocene or Pliocene. Mastodon, mirificus determined by Leidy 
from a specimen obtained by Clarence King on Sinker Creek is a 
Pliocene type. The remains of Procamelus might be Miocene or Plio- 
cene. Horn-cores of antelopes, obtained with rhinoceros material near 
Boise, represent a Tragocerus-like type known in America only from 
beds of Pliocene age. Castor is known from the upper Etchegoin of 
the western border of the San Joaquin Valley in California. A very 
large machaerodont cat found in an Idaho exposure on the Snake 
River southwest of Caldwell belongs to a type nearest to Ischyrosmilus, 
presumed to represent the Tulare stage in Calfornia. 

With our available knowledge of the mammalian fauna of the 
Idaho, determination of this formation as Pliocene is apparently 
supported, but beds both older and younger than Pliocene may be 
included in the localities from which material has been secured. It 
is highly desirable to have careful collecting work carried on by 
trained investigators in the bad-land deposits over the entire area 
presumed to represent the Idaho formation. 

Compared with other faunal assemblages referred to the Pliocene 
of the Great Basin province, the Idaho fauna of the best known 
locality in the Snake River region exhibits a relatively advanced stage. 
The horses find their nearest relatives in the Pleistocene and in the 
Pliohippus proversus zone of the Upper Etchegoin Pliocene. The 
deer of the Idaho are possibly related to those of the Upper Etchegoin. 
The cat is nearest to the ?Tulare Ischyrosmilus. The Idaho stage is 
evidently later than any other described Pliocene faunal zone of the 
Great Basin province. 



434 University of California "Publications in Geology [Vol. 10 



The Pliocene faunas of the Great Basin region clearly represent 
at least three quite distinct stages : the Ricardo, the Rattlesnake and 
Thousand Creek, and the Idaho. The Ricardo fauna, including as it 
does Merycodus, an oreodont, and several other forms of middle 
Cenozoic type, is certainly older than the Thousand Creek, Rattle- 
snake, and Idaho, in which these forms do not appear. 

The Thousand Creek and Rattlesnake are evidently of approxi- 
mately the same stage. In neither fauna is Merycodus represented, 
and no oreodont remains are known. The antilopine type represented 
by Merycodus in the Ricardo is expressed in various forms of Spheno- 
phalos and Ilingoccros. The hipparions of the Rattlesnake and Thou- 
sand Creek are apparently a more advanced stage than those of 
Ricardo, and incline toward the Neohipparion rather than the Hip- 
pariou type. 

If, as seems necessary, the Idaho fauna be included in the Pliocene, 
it must be considered as representing a much later epoch than any 
of the other Great Basin stages. The presence of Equus and Cervus 
and the absence of Pliohippus indicate a stage verging on the Pleis- 
tocene. 

The three Pliocene stages of the Great Basin province may be 

arranged as follows : 

Idaho Equus-Cervus? zone 

Thousand Creek-Kattlesnake Sphenophalos-Neohipparion zone 

Bieardo Hipparion-Meryeodus zone 

Great Plains Province 

In the Tertiary deposits of the Great Plains region a much larger 
representation of the Pliocene mammal fauna is found than has been 
thus far secured in the provinces west of the Rocky Mountains. Two 
or